JFC, anyone else getting an error where whenever they try to edit a post and tap anywhere on screen it'll hit the delete button instead? It's starting to get really irksome... Repost:
Fingerprints are easy enough to wipe off, I dunno if screen protectors help with the heavier oil from people that put their phone up against their face a lot etc (my mother's Moto always looks disgusting, sorry mom)... I haven't used one in like 5 years.
I had one on my EVO, none on the 2 phones after that nor my Nexus 5... Screen protectors are a lot like lens filters for camera lenses; unless you spend a lot of time at the beach, near construction, or another similar environment with fine grained particles you probably don't need one.
It's those fine particles that are MUCH more likely to scratch your phone than something like keys or an errant hit by whatever (not that I'd advise slipping it into the same pocket as keys, but still).
I've dropped my Nexus 5 plenty towards the end of it's life and the TPU case always kept the screen far enough away from any surface contact that could scratch it.