I have a small collection of different types, Sovteks, GEs, JJs, TADs, EIs, Penta (tung sol).
I really like Tung Sol and EI. The 12AX7LPS is great if you want more gain. But it completely depends on the amp and which direction you wanna go. Usually I take the amp out of the box and start combining different types - experimenting always brings me to a good result.
If you want some good and personalised advise, contact Doug (from Dougstubes.com). He knows most amps and knows what works. He sent me a set of new tubes for the Bogner Shiva, which was spot on!