I 2nd Telefunken 12AX7. Smooth plates is warmer and I prefer the ribbed plates with a higher resolution and high-end extension.
Looking for brighter tubes
Attention tube heads: I'm looking for brighter (more treble...not higher amounts of glow and chrome) tubes, if they exist. My amp (Jolida JD502P) has a well regarded bunch of Russian Tung Sol 6550s and 12AX7/12AT7s but I'm wondering if there's anything out there that imparts more sizzle in this amp. I do like the amp as it is...but hey..."rolling rolling rolling, keep them tubeys rolling...