Two of the best tubes are Mullard M8162 gold pin which is a military version of the Mullard 12AT7. Also the standard Telefunken 12AT7 and the long life 10 K hour Telefunken 801S. The 801S is very expensive, the Mullard is available in matched pairs for about $42.00 each.
I have tried several types of 12AT7's in my VTL 750 amps, including the factory versions, and in my opinion most aftermarket (old) NOS are superior that what was supplied by VTL.
Very generally speaking, if you want the most midrange detail possible, go for the Telefunken. If you want a warm relaxed midrange and bass with slightly soft high frequencies the Mullard is your best bet.
Please understand too, my comments about sound differences are magnified in my description to differentiate between these tubes. Real world, both are superior to the JJ and would likely make you happy.
Let us know what you choose if you do a shoot out.
I have tried several types of 12AT7's in my VTL 750 amps, including the factory versions, and in my opinion most aftermarket (old) NOS are superior that what was supplied by VTL.
Very generally speaking, if you want the most midrange detail possible, go for the Telefunken. If you want a warm relaxed midrange and bass with slightly soft high frequencies the Mullard is your best bet.
Please understand too, my comments about sound differences are magnified in my description to differentiate between these tubes. Real world, both are superior to the JJ and would likely make you happy.
Let us know what you choose if you do a shoot out.