The 325i made 189 hp/181 ft. lbs/tq. 1992 cars are non-vanos, 1993-94 are single vanos, 1995 is double vanos. (Vanos being variable valve timing, a la V-tech, on the intake and/or exhaust cams). Suspension is basically the same for all, with sport package cars getting a better set up and larger wheels. 1992s have gray bumpers, 1993-94 half body color/gray and 1995-on all body color.
The 328i didn't change much, although there may have been a different rear axle ratio for the 1996 cars, but I can't seem to confirm that.
A 328i would be the quickest.
If you are choosing between two specific models, let me know, as I have all of the specs for changes from one model year to the next (3-series Enthusiast's Companion from Bentley Publishing simply rules!), but neither the time nor desire to copy them for all years into this post.