Cary V12R Tubes

I would like to try different tubes for V12R. Currently I have Svetlana EL34. I want to know which one of the recommended output tubes (per manual it could use either 6550, KT-66, KT-77, KT-88, KT-90, 6L6) should I try and what sonic different for each would I get?
I put kt-88's (russian) tubes and after a very long break in time they sound super sweet.
SED el34's are superb...if you like a warm rich midrange. I currently run EH 6CA7 in AES Sixpacs and love them. They sound more accurate in triode than the SED and the highs sparkle more. According to Cary, the V12 was voiced for el34 tubes even though the others would be just fine.

I also have Tungsol reissue 6550's which I like as well --more linear and extended, but that el34 sweet midrange isnt there any more. A sweet looking tube for certain though.

Since the V12 is switchable between triode and UL, which mode do you prefer? The answer to that will help guide your decision...
JJ E34L blue glass the EH will give you slam but the EL will give you music.They have that magic midrange. Call for the lowest price.
Thank you all for your responses. The amp is almost always set at triode mode. Only one time I ran with UL a few years back. For some reasons (if I remember it correctly) it sounder too boomy and reminded me of a solid state amp. Sometimes I think getting the V12 was a little curse since it is expensive to try out different tubes.