screen protectors are kind of users choice as well..... they all do the same thing..... some are a little glossier..... some show smudges more...... etc etc...... in the end a $3 protector and a $30 protector are going to protect the exact same
as for cases...... thats wide open..... its more of an asthetically pleasing type deal..... decide if you want a then rubber bumper or a big bulky suitcase.... the real difference here is truely the protection..... the bulkier the better..... so its a tradeoff how much protection you want......
as for verizon cases vs att cases vs tmobile cases vs etc etc.....
most cases will fit any of them the same..... the phones between providers are nearly identical..... with 1 exception
the VZW phone is thicker due to wireless charging....... so a case designed for VZW will fit all the others...... but a case designed for ATT will be a little snug on a VZW phone......
for instance I bought a case designed for the others but I have a VZW phone.... its a 3 piece 'hybrid' (or bulky if you will) case...... it fits fine around the phone without a screen protector on it... however with the screen protector its just too tight.... bubbles constantly appear around the edges where the case is pressing against the protector........ I had to find a screen protector that was the perfect size to fit right inside the top shell of the case
but since you mentioned you dont have a VZW phone any case or protector should work for you.. in the end its all users choice
since you mentioned other accessories I will share my latest order.... I ordered an NFC speaker earlier..... in case you arent aware NFC is a close proximity wireless sort of like the little tag you use at gas pumps..... with this speaker you just bump your phone on it..... it turns on the speaker and also turns on the music player and bluetooth on your phone and starts your concert
