Whatever your preference is. The Titan Productions dub has those fake-y Japanese-y accents that plague so much of their work, but it holds nostalgia to some and has an arguably better script. The Frontier Enterprises dub is the one that was first aired in the U.S. on Sci-Fi in 1996 and is the one most people of the last generation have heard. The voice acting by Burr Middleton and co. is fairly cartoony, but it fits the tone of the film well and the lines are memorable. It has its naysayers, but I like both equally. A good restoration of AIP's cut from 35mm elements would be desirable as well.

Here is a direct video comparison of the two.