Speaker Recommendation for Classic Rock, Blues Through 50W Traynor EL34 Combo Amp

I'm looking for recommendations for a replacement speaker for my Traynor Custom Valve 50 Blue 1X12 combo amp.

I play two Strats (one with Custom '69 pups, the other with Texas Specials) & a Les Paul (with Duncan Alnico II Pros). My #1 axe is my American Special Strat with the Texas Specials.

I play Classic-Rock, Blues, Psychedelic, and Prog Rock, and am mostly a rhythm player, though I do also play some leads. 

My new (to me) amp is a Traynor Custom Valve 50 Blue (YCV50B) 1X12 combo, 50W & EL34 powered. It currently has a Blue Marvel speaker (I have no idea why!). I think the current speaker is holding this great amp back. The speaker lacks definition and volume, and seems a little muddy on cleans and at higher volume.

My target tone?: I'd love for my Les Paul to sound like Warren Haynes' or Billy Gibbons', and for my Strats to sound like Kenny Wayne Shepherd's or John Mayer's.

So, I am looking to get an 8 ohm, 12" replacement speaker for the Traynor that will work well for my type of music/playing, and also work well with the amp.

Based on web research, and watching some on-line clips, I was thinking of going with one of three WGS speakers: Veteran 30 or ET65 or Retro 30.

So, based on all this, which would you folks recommend as a replacement speaker for me?

Also, down the road, I'll be adding a 1X12 extension cab for larger venues, so, please also recommend a second speaker to go into the extension cabinet to be coupled with the speaker selection for the combo replacement.

Thanks in advance for your recommendations!