I really like the 19.5. I need to learn to shoot them better. I'm not a great handgun shooter but I developed decent groups with my Gen 4 19s through a consistent grip, trigger, etc. Now that I have Gen 5s...I need to redevelop muscle memory for the Gen 5. A lot of people are able to transition well from one gen to another...or even one platform to another...but it takes me a bit to gain proficiency. I haven't held the 17.5...but then again I haven't been interested in the 17 since I've found my fondness for the 19.