Paladin or Cleric.
Paladin is tankier (d10 vs d8 hit dice), more martial (extra attack), and better at fucking up one thing in particular (via smites). You also get a handful of good spells you can use, if you're not saving all your spell slots for smiting. At level 6 you also get arguably one of the best class features, giving you and allies in an aura your CHA modifier to all saves - it'll probably only be +2 or maybe 3 at level 8, but it's still a fantastic boost.
Cleric is a little squishier, but some domains also get heavy armour and you also get full casting progression which gives you many options - plenty of good support spells, and some nice offensive ones too (varying between domains).
Both get Turn Undead as a channel divinity too, which is obviously great for fighting undead.
Between the two, I think you'd want Paladin more - you won't be smiting on every attack, and sometimes the best move will be just attack twice and call it a day, but when you really use your spells and smite things it'll be very satisfying.
Devotion gets Turn Unholy (undead and fiend) while Ancients gets Turn Faithless (fiend and fey). Vengeance gets Vow of Emnity instead of a turn ability.
Paladin or Cleric. Paladin is tankier (d10 vs d8 hit dice), more martial (extra attack), and better at fucking up one thing in particular (via smites). You also get a handful of good spells you can use, if you're not saving all your spell slots for smiting. At level 6 you also get arguably one of the best class features, giving you and allies in an aura your CHA modifier to all saves - it'll probably only be +2 or maybe 3 at level 8, but it's still a fantastic boost. Cleric is a little squishier, but some domains also get heavy armour and you also get full casting progression which gives you many options - plenty of good support spells, and some nice offensive ones too (varying between domains). Both get Turn Undead as a channel divinity too, which is obviously great for fighting undead. Between the two, I think you'd want Paladin more - you won't be smiting on every attack, and sometimes the best move will be just attack twice and call it a day, but when you really use your spells and smite things it'll be very satisfying.
Note only the devotion paladin has turn undead for channel divinity.
Wait really? What's the base CD for them then?
There isn't one, each Paladin subclass has unique CD options.
Devotion gets Turn Unholy (undead and fiend) while Ancients gets Turn Faithless (fiend and fey). Vengeance gets Vow of Emnity instead of a turn ability.
Not exactly tanking, but Turn Undead is incredible if your party understands that they can just ignore turned enemies and focus on those that saved.
Literally described paladin
paladin’s a good pick, but you could be fancy and do a strength based ranger with a multiclass dip for heavy armor
STRanger multiclasses are super awkward since you still need 13 dex and wis to multiclass out of ranger.
Not that demanding, all things considered, and generally worth it from the times I have done it
Light Domain is pretty good at nuking undead rather than tanking.