I've got a G17Gen3, Gen4, and Gen5, so i don't have to prefer or wonder. Whichever I'm in the mood to choose to carry or shoot, I just do it. All three generations of G17 are all working fine for me.
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I was livid with my G17Gen3 when I first got it, due to excessive brass-to-face. Finally, after several thousand rounds, installing a #30274 (gen4) ejector cured it. Back then, I was mainly carrying a G22gen3, then G22gen4, but I did want that G17gen3 to function correctly.