The Glock 19 is a 9mm which is a compact that holds more rounds than the 26 which hold 10 rounds and less than the 17 which hold 17 rounds where the standard Glock 19 holds 15 rounds here's more on the Clock 19 Glock 19 | Glock 19
The other weapon you mentioned is a 40 caliber (more expensive) but less than good 45 caliber, and as mentioned by other posters what do you really want in a pistol? Conceal ability, stopping power, cheaper ammunition, all must be considered to answer your question!