Funny this thread got resurrected... Since it is, I'll give my input.
Not even sure these were made when this thread left off, but the
Psvane Treasure Mkii Kt88 are great.
The new stock Gold Lion are more overall lush, but lack the micro-detail of the Psvane kt88.
Flip side, Psvane kt88 isn't lush or forgiving like the GL.
Apart from kt88, I've tried various 6v6, 6l6, kt66, kt77, 6550, 5932, 6384, el34, kt120, kt150.
Great series of tubes to use in an amp (beam tetrodes / pentodes).
If the amp is spec'd correctly, you can cross breed 6v6 to kt150 with biasing.