Got to shoot both the Gen 5 Glocks and a P10c yesterday.
I was able to shoot both a Gen 5 17 and then later a 19. I shot maybe 20 through the 17 and maybe 40 or so through the 19. The trigger is nice and the difference is definitely noticeable. Didn't really notice the revised grip either way. The finger bumps on the Gen 4 actually fit me pretty well. Didn't notice the flared magwell much either, but only did a few reloads to see if I would notice anything. From that limited experience, I would say that they are nice, but not enough for me to go out and get one soon. I've been wanting a 19 for a while and when that urge becomes too much to ignore, I'll get the Gen 5. Even if it means that I pay a slight premium over the Gen 4, or what I paid for the Gen 4s that I have.
The P10c was nice, but it didn't floor me. The trigger was nice, but I like the trigger on my PPQs better. The reset also had a weird filling. Sort of felt like something pushing the trigger forward just before the reset. Difficult to explain. Not good or bad, but just different from the reset on my Glocks and PPQ. The grip texturing however was pretty aggressive. Particularly the texturing on the backstrap and sides. During recoil, I could feel it almost trying to rip pieces of skin of the meaty part of my right hand thumb. Similar sensation when I shot the CZ 75 SP-01 Shadow with the grip panels that it came with.

I guess I'm used to aggressive front strap serrations, but maybe not the sides. It's WAY more aggressive than the Gen 4 Glocks. Something that I think I could get used to. Maybe if I were shooting more often.
As for accuracy, they are both plenty accurate for me. The P10c has FO front sights, which was nice. The Glocks had the stock plastic sights. I didn't really notice a difference with the "newer/improved" rear sight look on the Gen 5 Glock, but I haven't really shot Glocks much with the stock plastic sights. If I had to pick which one I shot better, if would probably be the P10c. Both are really nice guns though.