As someone who has played both: Fighters are definitely much more playable in 5e than 3/3.5. This is mostly because of two reasons, really.
First of which is casters in 5e aren't as crazy powerful as they were in 3e, so fighters are able to "keep up" much better than they used to.
Secondly, fighters have a few key powerful features that really help them shine, and no longer require very specific feat chains to actually....do....anything. On top of that, subclasses, which are kinda like baked in PRCs, help a lot in giving extra abilities and build diversity, without sacrificing main class progression like they did in 3e.
That said, build diversity overall is much more limited in 5e, because there's not the glut of expansions like we saw in 3e (you can argue that this is good or bad IMO, i dont think either side is inherently right or wrong)
A 5e fighter gets another feature called "action surge" which let's them perform another full attack action once per short rest. This means that each time they get another attack, their damage potential for a single round of combat goes up by two attacks. This makes them about the best focus-damage Nova builds.
Well, outside of conjure animals and paladins because WotC fucked up hard with them (but that is getting fixed in the 2024 revision).
They pretty much just get to attack without a subclass. All their abilities just enable more attacks. Eldritch Knight is just a 1/4 caster. BM is one of the best, but they just get a few special attack moves like disarm.