I currently own three Gen 2s, REALLY like the no finger groove option. I have owned two Gen 4s, really liked the smaller grip option. Have owned six Gen 3s, liked them also.
I like the Glock 19 period. But currently, the no finger option gets the nod.
For my 50th birthday next year, I am thinking of sending a 3rd Gen 19 to Bowie Tactical and having a grip reduction and finger groove removal done. It might just be the perfect 19 (at least in my eyes