I assume you mean "GE
or Tung Sol 6550's".
All of the old tubes have strong factions proclaiming them "best", but again I'm of the opinion that old tubes are/were better, but "best" is subjective. "Favorite' is probably more appropriate.
Personally I think the best sounding tubes in that family are old GEC KT88's, but you need to take out a second mortgage to buy a matched quad
if you can find one at all. I used to run EI KT90's, nice clean tubes but I had problems with consistency, and they got real hard to find a few years ago. I don't know who even offers them new anymore, I think maybe EH.
Anyway, overall I've had the best luck with JJ KT88's as far as current production. I'm running a quad of reissue Gold Lions in a Reeves Custom 225, one of them flamed with very low hours, but other than that they seem to be sounding very nice. Kind of pricey, I don't know that they are appreciably better sounding than the JJ's that came stock in the amp, and I've never had a quality issue with the JJ product.