Mitre Circular Saw blades for cutting Oak floorboards
I'd use the 24 tooth blade, but be sure it is a carbide type and sharp. Since all your cuts are end cuts and will be covered with baseboard trim, so getting an ultra smooth cut is not that important. Obviously, you don't want to see any large chips on the cut edge, so do your cuts slowly and smoothly. Save your 48 blade for visible finish cuts on softer wood. If you do plan to do any precise finish work, moldings etc, consider investing in an 80 tooth blade for that type of work.  Good Luck.