My most accurate Glock has actually been my Glock 20 with .40s&w conversion barrel, just edging out my 17L.
My 17L has been shooting very well from a rest, shooting 2" with Winchester 147 fmj-fp (25 yards).
I swapped out the extended mag release for a standard one, and added a NY-1 trigger return spring (I don't like light trigger pulls).