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)