I've owned a: Gen 3 22, Gen 3 17, Gen 4 Glock 35, a not-a-Glock Polymer 80 G19. I think my favorite is a G35 (it would be a G34 if I had one) or the G35's Gen 4 frame with a G17 slide on it - which I do happen to have.
Between Gen 3 and 4, I like Gen 4 better. I notice the slimmer volume of the grip in the aft-to-front dimension. As much as people think a Gen 3 glock grip is a "brick", boy the untextured P80 G19 sized one is even more blocky in the grip contour in comparison.
I don't carry a Glock so I didn't feel compelled to try Gen 5, especially not with the extra cutouts.
I have always been curious about G19's. I want to see if the grip feels like the G17 but cut short, or if there is a curve that isn't there in other models. For example, when I was looking for my first IWB carry pistol I shot a G26 at the range (Gen 3) and there was a really severe "hump" in the grip that felt strange. Funny thing is, I shot it better than the others but went with the M&P40c at the time just because it felt more like other pistols I had shot.