There are a ton of good-to-great 3*s in all classes that have some. To wit:
Saber: Caesar (excellent stargen with Crocea Mors; Incite and Charisma can make whoever you make crit crit a hell of a lot harder)
Archer: tons, but David (1-hit Evade for the entire party - blocks any AoE NP and is still damned useful against single-targets; also his NP gives Sure Hit to himself for the turn) and Euryale (basically the 5* Orion but cheaper and better in nearly every way)
Lancer: Cu, natch (Divine Protection from Arrows and Battle Continuation can mean a solo Cu can last for a good long while, and Gae Bolg is no slouch in damage, even for a Quick NP)
Rider: Yoshitsune (aka Ushiwakamaru; party NP and attack buffs!)
Caster: Hans (there's a reason why people tell you to run him if you don't have Waver, Tamamo, or Merlin; and that reason is buffs out the wazoo with his NP)
Assassin: Cursed Arm Hassan (reasonably good stargen, instant-kill NP with higher chance than Jing Ke's)
Berserker: Lu Bu (if you can get off his NP, it's one of the strongest around right now)
Shielder: Mash, obviously (taunt, invincibility, and damage cut make her - even as she is right now without her true NP - a defensive powerhouse)