Re: 6L6s or EL84s for LP blues??
You can't just say a tube does this or that. It really all depends on the design of the amp. Yes, certain tubes have certain characteristics but a Vox AC30 makes EL84's sound good to me. I don't think an amp with just 2 EL84's has enough clean headroom, if I was going with EL84's I would use 4 of them and big iron. Also cathode bias but with a low B+ to save the tube life.
My favorite tube is the 6V6GT, they sound very close to 6L6 tubes. There are different 6L6's too. 6L6 amps have a lot more flexibility, they can do clean great and they can do distortion very well too. Again it all depends on the design and the iron(transformers).
I have also heard some good things about orange amps with the El84's, but I really like the Vox AC30. Overall I am not a big fan of EL84's, most amps that use them sound horrible as in the PV, Crate, low powered fender amps. They use cheap parts and smaller transformers. With those tubes it's a recipe for bad tone.
I think you can't go wrong with an old BF/SF Bassman slightly modded. If done correctly they can do anything well. They can do clean hooked up to a 15" JBL type speaker or they can do Marshall tones hooked to a cab with greenbacks in it. Same for a Deluxe reverb, you can make them do just about anything with the right tweaks and speaker, even the reissues.