Bought it, Sold it
The Classic Sentinel = Been a fan of sentinels since GTA 3, but it's more of a drift car, the ass of it swings around too much for my taste. Had it all of about 10 minutes.
The Coil Cyclone = The acceleration of that thing is... orgasmic. Unfortunately it doesn't corner worth a damn. Got rid of it after a day.
The APC = I was thinking this was going to be the solution to Hydras... until a Hydra took mine out, easily. It's not hard to destroy on foot either. kept it for weeks, got rid of it.
The Dune Buggy = The gun on it is useless, it only fires in front. A slight nudge from anything... another car, a rock, a hard enough gust of wind, and it fishtails. Got rid of that after several hours.
Faction = I like old school Buick Regals, I had 2 of them. It's not very fast though, and after taking it to Benny, it rolls over easily. Sold both when I needed the money.