2024 has done a lot to boost Martial skills fighter2 is more than just action surge, so what build is the best?
Still needs to function in combat (Eldritch Blast + Agonizing blast+Hex at minimum)
Depends on level range and if you are going single classed or multiclassed.
You would want Elf race with skilled feat. After that here goes:
Without multiclassing:
Level 1: Rogue
Level 2-8: Fighter
Level 9+: Rogue
With multiclassing here is my first cut:
Level 1: Rogue
Level 2: Fighter
Level 3: Rogue 1/fighter 2
Level 4: Bard 2/Fighter 2
Level 5: Bard 2/Fighter 2/Rogue 1
Level 6: Bard 2/Fighter 2/Rogue 1/Ranger 1
Level 7: Bard 2/Fighter 2/Rogue 1/Ranger 2
Level 8: Fiendlock 6/Fighter 2
Level 9: Rogue 1/Fiendlock 6/Fighter 2
Level 10: Rogue 1/Fiendlock 6/Fighter 2/Bard 1
Level 11: Rogue 1/Fiendlock 6/Fighter 2/Bard 2
Level 12: Rogue 1/Fighter 2/Lore Bard 3/Fiendlock 6
Level 13: Rogue 1/Fighter 2/Fiendlock 6/Lore Bard 3/Ranger 1
Level 14: Rogue 7/Fighter 2/Lore Bard 3/Ranger 2
Level 15: Rogue 7/Fighter2/Fiendlock 6
Level 16: Rogue 7/Fighter 2/Fiendlock 6/Bard 1
Level 17: Rogue 7/Fighter 2/Fiendlock 6/Bard 2
Level 18: Rogue 7/Fighter 2/Fiendlock 6/Lore Bard 3
Level 19: Rogue 7/Bard 2/Fiendlock 6/Fighter 4 - Boon of Skill
Level 20: Rogue 8/Fey Wanderer 3/Fiendlock 6/Fighter 4 - Boon of Skill
There might be better, but those are the best I think off the top of my head using only 2024 rules
If you allow 2014 subclasses, races and feats there is a lot more design space with things like Scout, Purple Dragon etc.