I have not found an EL34 that betters a KT77 but I have not tried the new production Mullard's.
As you are finding there are trade offs in power tubes, less bass but to die for midrange etc. A good while ago I picked up a pair of NOS Chinese ST 6550's that simply looked well constructed for $35. After some hours they became quite good. Balanced from top to bottom. I found out that they were spece'd by Mesa amps.