Ive gotta second the Fender SuperBassman ( and not because I have one for sale... seriously because if it doesn't sell I'm more than happy to keep it. I just have more gear that I need)
It has the lush wool of the Orange if you want it, and the muscle of the Ampeg if you want that. Its got features that are awesome (DI, Auto Bias, Selectable Channels etc). It has a ton of clean headroom and enough versatility and dirt in the OD channel that my board of 4 fuzz pedals and 3 overdrives gets put aside with it. AND its only 65lbs. I love it.
I just love my 300 pro more, and wish I didnt because its 20lbs heavier and its bigger.
of your list, I havent tried the Reeves, but trusted sources love it. The Ampeg VR is awesome, but not for me. Everytime I see some other musician play one I am in love with their tone, but its never quite been "it" for me when I had one. Its a standard for a reason. The Orange, with its design shortcomings, was an amp I LOVED. It sounded awesome live. It was thick, throaty and for me was exactly at the point where my playing dynamics made the difference between clean and wooly grit at live volume. Plus, its rather lightweight.
Ive had a Morgan too. It was a very nice tonal amp. I didnt like the extra deep bass on it because those low frequencies ate up the clean headroom and it would overdrive sooner than I wanted volume wise. Also, getting it serviced can be a REAL headache. Lets just say the world works on one calender system, and Joe Morgan works on another. Morgan seems to believe he invented an entirely new thing under the sun that everyone is chomping at the bit to copy and clone because he WILL NOT release schematics to your local tech. You HAVE to send it to him. argh.
As for the new Mesa... i just dont dig the aesthetics and I cant get past it.