Tar Heel to Tar Heel, here's what I think:
1. Upkeep of the room: as several others have said, this varies unit to unit. However, in general, Saratoga will be the most worn due to age, whereas OKW is recently refurbished.
2. Size of room: advantage Old Key West and then everything else. OKW has 2 queen beds and are the largest studios by far. Haven't stayed in a studio that I've felt cramped in (VGF, SSR, OKW, AKL - Jambo, BLT, BWV) but I haven't stayed at Copper Creek yet.
3. Food options at resort: advantage everywhere except for OKW. Only having Olivias and a quick service can be a little sparse on a long stay. However, you're only a boat ride to Disney Springs. Some of my personal favorites: Jiko at AKL; Turf Club at SSR is a hidden gem; BWV has the advantage of the entire boardwalk.
4. Transportation options at resort: advantage everywhere except AKL. Having only bus transportation is awful/exhausting. Additionally, it's a long bus ride to anywhere except Animal Kingdom. Monorail resorts are good, but of these, I prefer the Poly due to being able to walk to TTC to catch the monorail direct to EPCOT. BWV and BCV have walking paths and boat transport to EPCOT and Hollywood Studios. SSR is walking or short boat to Disney Springs. OKW is a boat or long walk to Disney Springs. BLT has a walking path to Magic Kingdom. CCV/VWL are a boat ride to Magic Kingdom, but bus everywhere else.
Conclusion: given your priorities, I believe that Poly or BWV would best suit your needs.
Go Heels.