A true Ameraucana would be a better sire, as long as he is from a line that lays blue, not greenish eggs. Rumpless birds often have fertility issues, seem the tail helps a lot with balance.
Another great option would be a Cream Legbar. It really depends on what other traits you are trying to fix because those birds are so different in many other traits. Obtain the blue egg laying bird that is closest to what other traits you are breeding for, getting rid of a pea comb, for instance, is a lot more work than just starting with a Legbar.