I have pretty small hands, so Glocks never fit me right until gen 4.
I have owned a 27. I couldn't hit the broad side of a barn with it. It was just way to snappy(that's coming from a guy that likes and owns .40s). Everbody I had let try it couldn't hit worth a poop with it...
I think the size of the 19 is pretty perfect for concealed and range time. I currently own both the 19 and 17 in gen 4s. One is American, the other Austrian. Neither have given me any problems and both seem on par in quality with each other.
I have recently moved into my 17 as my everyday carry. I don't think longer slides are harder to conceal, but taller frames are. So to get the best of both worlds(talking g19 and 17), I had the frame on my g17 cut down to accept g19 mags. This made the gun the same height as a 19 but I get the added advantages of the heavier slide(reduces felt recoil), the longer barrel(slightly more muzzle velocity), and the longer sight picture(more accurate shooting).
I really think a 17 chopped down to accept 19 mags is the best glock combo out their....but if you can't afford to do that, just get a 19 and call it a day(the 17 isn't significantly softer shooting, just marginally...I've shot them side by side).
As far as the XDs, I had a fair amount of range time with mine and it never gave me issues...mine had not been "fixed" either. I sold it because it didn't fill a roll I needed for me. I have the glock for all day carry and a Kahr cm9 for a grab and go carry when I don't want to take the time to put my OWB kydex on for the glock or HK....the XDs filled no voids for me, but I did trust mine. Mine ran great!
Obligatory photo...
17 is on the right.