Best IQ sensor sub-$2k used/new?

Ignoring the following facets:

Shutter speed/fps
Megapixels
ISO range (min. good IQ ISO 1600)

Which camera would have the best sensor sub $1000-2000? 1ds Mark II? 1D classic?

for canon, it's either 1dmkIII, 1dsmkII, or 5D. Take your pick. I have two of these and they are remarkably similar when scaled to the same size print.

Is it possible to jump into medium format for just $2k (body only-digital, not film)?

Doubt it. A PhaseOne 645 camera with a P25+ digital back and an 80mm lens costs approx $17k new. I don't think you can find any used system for under $5k.

my guess is 1Ds2 or 5D...this is a good question. You can ALMOST get a 5D2 for under $2k now. I have seen one ever under 2000 bucks, so be patient and look around

I sold off all my photo gear 6-7 months ago but I regret that decision as I miss my cameras dearly . I might even consider the switch to Nikon, but I'd still like to stay with Canon as I'm most familiar with their lineup/tech.

Whats the main difference between 1ds Mark II and 1d Mark III, aside from FF versus APS-C? Both are just under $2k. If I wait a bit, I might be able to snag one for $1.5k+.

I used to shoot a lot of action photography, but I would always strobe so FPS isn't the most important thing to me. AF and image quality is important - but as always PRICE is the *most* influential factor

I was going to say go for a refurbished 5D...but then I checked the current prices. Adorama has them now at $1699! I hadn't realized they went up that much. Ouch.