Best tubes for Conrad-Johnson MV-50 or MV-52?

I'm about to retube a C-J MV-50. Currently has four Svetlana EL 34s, which sound good. Would like to hear from other CJ owners about your experiences with EL34s and with the other tubes: the pair of 12AX7, and the pair of 5751. Reliability? Sound character? Good suppliers? My associated equipment includes a CJ PV-12 preamp and Vandersteen 2Ce speakers, with CD source. I prefer a sound on the warm, laid-back side, and listen mostly to classical. Thanks, and happy listening.