3×2 is small, but I think the grids are abotu 15″ which makes it around 4’x2′ – the minimum size we recommend for a small rabbit. Rabbits do prefer a larger area to run around, but it can also help to make multiple levels – a 3×2 condo with three levels would provide some area to exercise.
Personally, I prefer puppy playpens which are 4’x4′ (and you can move them around so they fit in whatever space you have – they don’t have to be set up in a square). They’re also super portable and easy to clean (since you can just pick them up and fold them).
I wouldn’t recommend a pet store type cage unless you plan to attach a pen that the rabbit has access to 24/7. My pair has a 4’x2′ pet store cage with a puppy play pen attached. I like the cage because it keeps the hay and litter boxes in an easy to clean area, but the cage by itself is way too small for either of my rabbits (4lb and 5.5lb)