I have the VR4.5's and have only tried a few amps - namely Simaudio W5, Parasound JC-1 and Aragon Palladium 1K. Surprisingly, I preferred the W5's by a VERY small margin. As for bass/midbass speed and clarity - all these amps had it in spades! You would think those monster monoblocks would stomp the W5, but no. The W5 just seemed a little less colored in it's sound. I think some people might call the W5 a touch dry sounding, I call it accurate and clean.
Also surprsingly, I preferred the 1K to the JC-1. The JC-1 seemed a little more harsh sounding in the mid/upper registers.
I've tried very few amps in my home because, quite frankly, I have been very satisfied with the sound.
All you choices are very strong. The only one I might give some pause to is the Mark Levinson. I thought about getting one a number of times but the reviews of their "dry" sound scared me off for the 4.5's.
Years ago, I did have a McCormack DNA-1 Deluxe in a different system and that amp was really nice sounding too. Unfortunately, and apparently NOT typical, I had reliability issues and subsequently sold it. Unfortunately, their newer offerings are a little pricey or else I might try them again...