The Sovtek 12AX7LPS is regarded to be a well-balanced, smooth-sounding budget tube with good detail and relatively low noise. I had a pair in my Pro-Ject Tube Box and was pleased with them. But they're supposedly more susceptible to vibration than some others, so that's why I asked what you were putting them in. These Mullard tubes are supposed to be a good budget 12AX7, too, without the design issue that supposedly causes the susceptibility to microphonics in the Sovtek tube.

http://thetubestore.com/mu12ax7.html

See also their opinion of the Svetlana 12AX7:

http://thetubestore.com/svetlana12ax7.html