Which would be preferable, an older Audio Research Corp. VT130 or a newer SS Rotel 1552?

Lose the preamp and use the AR VSi60 integrated.
There’s one for practically half-price here:
Audio Research VSi60 Stereo Tube Integrate... For Sale | Audiogon

Uhm the speaker/room synergy and your content is what should get you involved. The amp is there mainly to just provide voltage and current for your speaker tranducers to move air. So I don't get this sentiment about moving you @bigdoghoss 

Music is what moves you not an amp

Get a nice pair of used Joseph Audio Pulsars and you’ll never look back.  805s detailed but not involving — Pulsars detailed and musical.  No comparison.  Ditch the speakers cause no electronics are gonna fix what you’re missing. 

I agree with others that if you aren't loving the sound of your setup, speakers might be the best place to start. But maybe you already know that you love the 805, and you've heard them sound better than what you currently hear.

If that is the case I would say go for the Audio Research but only if you are prepared for the potential hassle involved. Buying an older high-end piece like that is kind of similar to buying an older high-performance vehicle. Both can be rewarding but also both can get expensive when it comes to repairs or maintenance. In this analogy the AR would be an older German performance vehicle. Great to drive but likely expensive to maintain. The Rotel would be a newer Lexus or Acura. Still quality overall, exchanging performance and character for reliability and low cost of maintenance. 

Easy for me. I would go for the Audio Research VT130. It will sound much more natural, organic and musical. The Rotel is punchy, accurate and neutral... but not as musical and organic.