TDK SA-X and Maxell XL-IIS.
I look for high bias and metal if I can find them, I've done some good recordings with the maxell xl II's. I have a few denon metal tapes I'm saving for a special occasion...like when I can find a decent 4 track..
All that said, I'll pretty much get any tapes as long as they're sealed.
Sony Metal-SR are the best and were fairly common in the mid-late 80s. ...