For under $2500.00, I would say the Matchless Laurel Canyon. The head retails for $2350 and the combo goes for $2510 according to their website. As for the why....without getting too technical, it just sounds like it isn't trying too hard to impress. It just delivers a really cool 60's-70's vibe and very nice mids! It's warm even when brite. Great for the stage or the studio.
Okay, as for up to $6K pick, that's a bit more tough! In the end I had to go with the Diezel VHX 100W. I don't really feel like I need to even justify the why part. I mean, just plug in and hear this thing sing.
-The Tone Ranger