what is the best Kt88 to get

Don’t forget how much tastes in sound differ.  Many may not like a certain tube's presentation, regardless of the application/component.

Interesting, I love the Preferred Series KT88s in my Rogue M-180s.  Overall excellent, colorful, dynamic, very good bass, with a creamy top end.  They replaced an octet of KT-120s.  

I did get them for nearly half price during a Black Friday sale.  Otherwise I would have stuck with KT120s.

PSVANE Gray Glass KT88s are the best I have tried. Even out do NOS RCA/Tungsol 6550s, GE 6550s  and all of the Russian Re-issue tubes.

I have been on the KT88-6550 search for a few years with a Mcintosh MC60. Penta, Psvane, JJs,TungSol reissues, and NOS TungSol 3 hole grey plates,, Sophia Electric KT88s and now some new Gold Lions.
I have some hope that the GLs will, after burn in provide me with accurate timbre and send the right signal to the subwoofer amps in my ZU Def 4s. It’s a tradeoff. NOS TungSols are glorious in so many ways but give a subtle softness in the bass region and with the speaks lose a touch of punch. Rolled in different input and driver tubes to tighten up the bass.
Hoping the GLs prove out to be the best balance. Surprisingly, the Tung Sol reissues provide the best shove and overall dynamics, bass included, and every time I reintroduce them I like them. Put the NOS Tungsols in and it’s very musical. Pents, Psvane, JJ all too hard.
The Zus are very revealing and their is no doubt as to the differences. More than ever after reading threads on this, unless you can reference the amps being used as well as the speakers-just say each persons reference point has to be different, so yes Rodman,opinions of the different tubes come out differently.