Should I use waterproofing product or caulk at the base of my foundation walls?
The waterproofing material's spec sheet will tell you how wide of cracks it's designed to accommodate. That should be your guide. If your joints are wider than that, move to a caulk. If they're extremely wide (over 3/8" or so), consider a rope caulk or a masonry patch product as support for the sealer product.