Had experience with all 4 155s, the 2.0 ts 8v, 16v, Q4 and v6.
The 2.0 Ts 8v is the most civilized, nice to drive, very neutral handling compared to the nose heavy 155 v6.
The 2.0 Ts 16v feels similar, lacks low end torque in my opinion but compensates once it gets past 3500rpm.
The Q4 can rearrange all of your organs, both while accelerating and while cornering. Not very comfortable to be honest, has a much harder ride compared to the rest. Great fun for the track!
The v6 for me was the best of all 4, good power delivery, acceptable cornering and sweet noise. Very reliable compared to the 16v and the Q4, not sure if it is as reliable as the 2.0 8v (chain driven cams) but must be close.
Most people think that the difference between the 2.0 8v and the 16 is not much, same when comparing the 2.0 16v to the v6, but trust me, they feel and go completely different.