12ax7 vs 5751


hi all,
i need some advice. i`m very new to tube amplifiers and i`ve been doing some tube rolling.

i currently have a pair of grant fidelity matched psvane 12ax7t`s in my amp which sound fantastic.

what i`d like to know is which are the better tubes, 12ax7`s or 5751 tubes. i`ve been looking at forums and there are folk out there that say 5751 tubes are better than 12ax7 tubes.

can i have your thoughts on this please and also which are the good 5751`s to go for.

i really like the psvanes but if they can be bettered i`d go for it as my next line up of replacement tubes.

my amp is a yaqin mc100b. the tubes i have installed at the moment are.....
2 x psvane 12ax7t`s
2 x brimar 6sn7gty/cv1988`s
2 x sylvania 6sn7gtb`s
4 x electro harmonix kt88eh`s

many thanks in advance guys.
grayf
oh i forgot to mention (yet again as usual lol) i did order a pair of 12ax7`s earlier today. very cheap too! i ordered a pair of golden dragon 12ax7`s. heard some very good things about these and they`re the second cheapest tubes i`ve ordered too! i should have them within 48 hours so i`ll let you all know how they sound.
oops need to correct a mistake! the chinese dragons are ecc83t`s the "t" standing for trustworthy
I have the golden dragon 12at7's as the stock Thor tubes.

What is the difference between 12at7 and 12ax7 ?
What is the difference between 12at7 and 12ax7 ?
I asked Brent Jessee that question but added the 12au7 also. He said the 12ax7 has the highest gain followed by the 12at7 then the 12au7.
X
Does that mean they are interchangable? If so I wonder which is preferred...less gain/more volume OR more gain/less volume.
It was suggested to me that the 12at7 Golden Dragon tubes may be my weak link.