My posts only represent my personal opinion and do not necessarily reflect the opinions or official policies of any employer, past or present. Obvious spelling errors are likely the result of an iPhone keyboard.
The biggest mechanical advantage held by the 45 over the 19X is the addition of the breach face cut. Makes extraction and subsequently, ejection more positive. The 19X looks cool but the function is what wins. I choose the 45.
"Knowledge is good." Emil Faber, date unknown.
I'm with rangerover: I really, really like my 19X and actually prefer the lip below the frontstrap (some people have cut theirs off to accommodate Gen 5 floorplates) because I don't get my pinky pinched on reloads. I like the shorter slide for reduced pinching IWB or AIWB.
I could be happy with a 45, though.
G45 > 19X because of the magwell lips and it comes with MOS.
I have a 19X and 45. If I could only have one it would be the 45 due to all mags being interchangeable. If that wasn't an issue I would opt for the 19x. The front grip turns more which fits my hand better at the bottom: as a result my grip is tighter and I shoot it better. Other than that the G45 is the choice.
I carry a 19X everyday, at least until my 43X MOS arrives at my dealer. I think it is the perfect of the double stack 9mm Glocks.
The 45 is the slightly updated version that is available with an MOS cut. For that reason I would recommend a 45 MOS instead of a 19X. Along with the aforementioned breach face cut on the 45 to force better ejection. My 17 G5 MOS launches empties into space.