What, in your opinion is the best vacuum tube regardless of family you have heard in any amp?
Normally I love the midrange on the Amperex 6922's (I have a set from 1964) but in the Lyr they just did not sound right. They were strained and almost distorted sounding, as if the amp was driving them too hard. I swapped in a new build set of Genelex Gold Loin ECC88's and the clarity returned, plus the Gold Lions had much better bass. It could be just the way the particular sets I own worked in the Lyr because the Amperex set went back into my main stereo preamp and they sounded as sweet as always. But the Gold Lions sounded good so I'm sticking with them for the Lyr. Plus they are relatively inexpensive so that's a plus. :)
A tube's performance depends greatly on the circuit. If it's properly optimized for the tube in hand, then fine. If not, then you're going to get distortion/performance differences.