Since I got my G26 and have been carrying it AIWB in a nice holster I've wondered why I didn't get one years ago. It seems to do everything really well, and is very 'shootable' just like the larger 19. Because I carry appendix style, I'm glad I got the shorter 26 instead of the 19, just for general comfort (especially while sitting or driving).
Also, the 26 can go 'bigger' with extensions, and can also use the larger mags of the 19 or 17. The 19 can't go 'smaller', and can't use the smaller flush 10 round mags of the 26.