Ok, we need to know what kind of tones/style you are going after before making suggestions. The "best tone" is highly subjective, and the reason why we all sound different.
Nominally, there is nothing wrong with your setup. So what about it sounds "bad" to you?
My two cents is this: a simple replacement speaker in old Princetons, really makes a difference (in most vintage Fenders, actually. I always do this). If you are using an attenuator, you probably are cranking the amp, which is great. The JJ 6V6 tubes in your Princeton may be a culprit. You see the JJ 6V6S is not really a true 6V6. They sound great to me, but maybe you would prefer something more vintage correct like a pair of Tungsol 6V6GT.
You may also want to consider upgrading to a WGS celestion equivalent speaker to tame the highs, tighten the lows, and make the mids a bit more pronounced.
This is all pure speculation since we have no real guide as to what is "wrong" with your tone, and where you want to be.
Amp: Firebird Musical Amplifiers
Guitars:62 LP SG , 02 FB VII, JB FB I, 76 Electra Omega, 64 Firebird V, 73 LPC, 61 Custom Tele, 59 and 60 Melody Maker
Effects: Mythos Chupacabra, Strymon Deco/Flint