I most often use prehnite and gold sheen obsidian. I just resonate very well with prehnite, and the gold sheen obsidian is particularly useful in that it can ground you without blunting your psychic edge. They're very good for normal daily readings.
Next are the usual suspects: amethyst, labradorite, and moldavite.
Among the more unusual stones I use are dumortierite, iolite, pietersite, and almandine garnet.
Prior to a reading, I select and then wear whichever stone I feel will be apt for its energies.
Btw, in the Stone Property Reference Index in the Pocket Book of Stones by Robert Simmons, he lists the following as particularly useful for Tarot: creedite, dumortierite, herderite, iolite, and pietersite. I plan to collect all of them.