Fighter Subclasses - PHB

 The Fighter is kind of a weird class. In terms of specific features the class itself gets, most of them are extremely simple - Indomitable, more than 2 attacks (if you get to level 11,) Action Surge, and, sneakily, getting two more ability score improvements than normal classes would get (Rogues get a single extra one). But unlike the Ranger, the strength of the class is not so much limited to the subclasses, as much as it's just that Fighters in general are very good at the fundamentals of D&D - attacking things with weapons.

So, then, what do those subclasses bring?

Let's start with the Battle Master.

First, a caveat: it's pretty clear that WotC likes this subclass the most. And it's not hard to see why - it's very customizable, and has a powerful core mechanic that is also satisfying to use. Arguably, the subclass veers into Hexblade territory - where you have to kind of justify yourself for picking a different one. I suspect that a 6th Edition might make the Maneuvers the Battle Master gets into a core Fighter mechanic, or expand it to other martial classes. But let's take a look at the options.

At level 3, you get Student of War, which gives you proficiency in an artisan tool of your choice. A very DM-dependent skill, but nice.

You also get the core of the Battle Master - Combat Superiority. You get four d8s that are your superiority dice, which you can spend on maneuvers and regain them all after a short or long rest. You then learn three maneuvers from a list, which is long enough that I'm not going to go into it here. Most let you use them after you hit with an attack and add the roll of that die to the damage, while also getting some extra effect like knocking the target back or giving the next ally advantage on an attack against the target - though some are non-combat things like getting a boost to a Charisma check. You get a 5th die at level 7 and a 6th at 15.

At level 7, you learn two more maneuvers as well as getting the extra die. You also get Know Your Enemy - while you observe a creature outside of combat, you can learn if they're superior, inferior, or equal to you in Strength score, Dexterity score, Constitution score, Armor Class, Current hit points, Total class levels (if any) and Fighter class levels (if any.) (Granted, "class levels" is less of a thing for NPCs in 5th Edition, but you get the idea.) Like the artisan's tools, this has narrow applications, but the extra maneuvers and die are more of a great thing.

At 10, your superiority dice become d10s and you learn two more maneuvers. While this might look dull, you can think of each maneuver as a new class feature, so this is actually pretty fantastic.

At 15, you learn two more maneuvers and get another superiority die. Additionally, if you roll initiative and are out of superiority dice, you regain one - that nice "recharge" thing that a lot of classes have to wait until level 20 to get.

Finally, at level 18, your superiority dice become d12s

This is a great subclass - one I haven't yet played, but I'm intending to multiclass my Gloomstalker Ranger into this at level 6. Much as I love how your can customize the Warlock, this is a great class for people who want to build something unique.

Next, we go to the Champion. The Champion, to me, is the subclass to hand someone if they are nervous about complex rules and features. It's not underpowered or anything - just very simple and straightforward.

At level 3, you get Improved Critical - you crit on 19s or 20s, meaning you're going to crit twice as often, which is pretty great. (And makes this a great 3-level dip for a high-level Barbarian.)

At level 7, you get Remarkable Athlete. You get to add half your proficiency bonus (rounded up) to any Strength, Dexterity, or Constitution ability check that you aren't already proficient in. In addition, your long jump increases by a number of feet equal to your Strength modifier. Having Jack of all Trades for Sleight of Hand or Stealth is pretty nice, though given how few Strength and Con checks you'll make (and as a Fighter there's a good chance you're already proficient in Athletics,) this is a bit minor.

At level 10, you get to choose an Additional Fighting Style. I'd look at some of the new ones in Tasha's for some more interesting options - Blind Fighting means never getting ganked by an invisible creature again, and you can tell the caster to drop a darkness spell on you to become an unholy terror.

At level 15, you now crit on 18s, 19s, and 20s - so, a 15% chance at a crit, which is a lot more than most.

Finally, at level 18 (yes, fighters get subclass features at 5 different levels, making them the anti-Bards) you get Survivor. If you have half your max hit points or fewer at the start of your turn, you regain hit points equal to 5 plus your Constitution modifier, as long as you don't have 0. This is pretty great - consider that if you are out of combat, you'll always "idle" at no less than 50% hit points, and you'll get some nice passive healing over the course of a tough fight, which your healers will really like.

Again, the Champion is a fine subclass, if a little boring. A great "my first D&D character" option.

Finally, from the PHB, we get the Eldritch Knight. This is actually the class I've played the longest, so I have the most insight into it. You can build a very tough tank character from level 3 if you just take the shield spell - heavy armor and a shield plus 5 AC on demand is really good. That said, if you want to be a real "battlemage" who weaves powerful spells between weapon attacks, I'd recommend going for some other option like a Bladesinger Wizard, Hexblade/Pact of the Blade Warlock, or Sword/Valor Bard - your magic is supplemental here. Also, pick Green Flame Blade as one of your cantrips if you are going to be a melee EK.

Ahem.

At level 3, you get Weapon Bond. You can, over the course of one hour, bond with a weapon. While holding it, you can't be disarmed as long as you're not incapacitated, and if it's on the same plane of existence, you can summon it back with a bonus action. You can have up to two weapons bonded at a time - ending the bond with one if you bond with a third. This is actually very useful for a number of reasons, one of the biggest being that you don't get to use your weapon as a spell focus for most of your spells, so you'll need to drop it in order to cast anything with a somatic component (unless you have an off-hand free - really this is mainly a problem for someone like me who goes with a weapon and a shield.) Warcaster is thus a very useful feat for this subclass. (Note that the somatic component for the SCAG cantrips like Green Flame Blade and Booming Blade is your weapon, meaning the somatic component can be performed with your weapon hand.)

Additionally, you get Spellcasting. Your spellcasting ability is Intelligence, and you get access to Wizard spells. However, there are two big limitations. First, other than the four spells you learn at 3rd, 8th, 14th, and 20th, they have to be from the Abjuration or Evocation schools (though that will cover most useful combat magic,) and also, you're only a "1/3 caster," meaning that you'll only ever get 4th level spells, and you don't even get 2nd level spells until level 7. However, unlike half-casters Paladins and Rangers, you will get cantrips.

Notably, Action Surge actually lets you get around the usual "can't cast a leveled spell as an action and as a bonus action" thing, because both spells are actions, meaning that when you hit level 13, you can cast two fireballs on the same turn.

At level 7, you get War Magic. When you use your action to cast a cantrip. you can make one weapon attack as a bonus action. This makes those SCAG cantrips like Green Flame Blade really good, because you effectively get two attacks anyway, only the first has extra effects. (The math gets more complicated once you hit level 11, when your cantrips level up again but also you get a third attack, and again at 17, when the cantrips upgrade again, and again at level 20, when you get 4 attacks.)

At level 10, you get Eldritch Strike. When you hit a creature with a weapon attack, the creature gets disadvantage on the next saving throw it makes against a spell you cast before the end of your next turn. At level 12, I have yet to actually use this, only because I tend to reserve my spells for defense. But given that your Intelligence is likely to be a low stat priority, making foes a little more likely to fail against your spells is nice to have should you need to blast them with something.

At level 15, you get Arcane Charge. When you use your Action Surge, you can teleport 30 feet to an unoccupied space you can see. Teleports are always useful, and give you a bit more battlefield maneuverability, which is nice.

Finally, at level 18, you get Improved War Magic, which works the same as the old one but now on any spell - not just cantrips. So, you can fireball the target and then hit it so that it will get disadvantage on the fireball you cast next turn.

I will say that I think the Armorer Artificer does most of what I like for the tank-focused Eldritch Knight but better, but give the choice of spells and the versatility of the fighter, this is a pretty nice, customizable subclass.

Next, we'll take a look at the weird SCAG-based Purple Dragon Knight, along with the subclasses in Xanathar's. After that, we'll take a look at Wildemount's awesome Echo Knight along with the options out of Tasha's.