With gear other than a Candela, I've really enjoyed my NOS Raytheon 12AU7A Blackplates (and NOS Baldwin/Raytheon), NOS Baldwin/Sylvania 12AU7A and NOS Baldwin/RCA 12AU7A. As well as just plain NOS RCA 12AU7A.
Each one delivers the music a little differently, but they all sound wonderful.
Depending on your system and personal preferences.....YMMV.
And yeah, those NOS RCA Cleartops (with side getter) are some sweet sounding, special tubes. Some have said they sound too bright. But I have found that if you play them in (I guess burn them in is a better term) for a good 50 hours or so, they really sweeten up and even develope a slight warmness that just sounds beautiful). Again, that's in my system. YMMV.