Lancers beat all other cav, straight up, except Gothics. Gothics are slow. Kats are good but at V0 have poor morale, and are slow.

Two of my favs are on the list, Szekely are great cav archers, fast and can fight. Pronoai Allagion are very similar to Feudals and are a great addition to the Byz arsenal.

Alans are another great cav, very useful under a lot of conditions.

and Camels, which are oft maligned, can really hurt any cav if used properly.

That said, there is no 'best' cav, each has advatages (some more than others) but also disadvantages. Gothics in the desert, for example. It's all about using the cav you have correctly.

ichi