In general, loose is considered better because you can install more and reduce the load on each bearing. The old fill the race and remove one adage of years ago still holds true and will almost always result in one or two more bearings in there then caged. (I'd do this first with the spindle and left side cup dry. Load the bearings, then push the spindle in firmly and rotate. Easy way to ensure you don't have too many. (Oh, yeah, you can skip this and just do it for real, but 1) it will be far harder to feel anything and 2) if you do need to remove one, fishing it out is a messy bear.

Edit: a little fun. Caged vs loose bearings? (You'll find those free roaming critters on any shop floor.)