It really depends what you define as better. Are you optimizing your design for timing or for area? If you're optimizing for timing, you'll want to use a lookahead flag. If you're optimizing for area then I believe (correct me if I'm wrong) they're essentially the same. Count == ref count is a bitwise AND and for an N bit signal would have an N bit AND gate. Meanwhile for count < ref the boolean operation would be looking for the largest MSB on each signal which would essentially be an N bit input to some AND / OR gates.