welcome to GT !!!!! get the 19
This! that being said.. i love my 19.. not as big as the 17 and it feels sooooo good in my hands. 26 is great for carryingIt depends upon your application....
If concealment is not a concern, and just want to shoot quite a bit, get the 17 or a 34.
If concealment is a concern, get the 19 if you are shooting a lot - if you are CCW and shooting enough to remain proficent (but not a lot, or you reload) get the 23 - the .40 caliber really is more effective than a 9mm for SD.
If concealment is a major concern, get the 26.
The Glock really is a tool - intended to be used "day in and day out" and remain reliable - rain, snow, hot, cold, dirt, sand - crawl under a car or house. It is not a work of art that must have the fingerprints wiped off every time it is touched.