The only time I used a 19 was during the 7 months of academy. As the academy required that you use their pistol.
I had previously carried a g17 while working for an armored truck company and knew that once I was through academy that I would be switching back to the 17, it just fits me better.
My department allows several Glock models, Sig's, h&ks, s&w.. I can't ever imagine myself going away from the Glock 17 though.
-Jake