While the Mesa is a great cab you might find an old Eden XLT in good order quite cheep, because they are so heavy fewer people will want to haul one these days, just check the cones for creases, if they haven't been heavily abused they go on for ages.
If you want astounding downstairs you can find an XST later to couple with it.
Lots of people say that is a hell of a good combination of tone for a rock bass rig, I have the old 8X10XLT three port cab which I couple with a pair of Ampeg SVT115's.
I know it's against the rules but they don't seem to be out of phase at all.
The clarity of the Eden compliments the thickness of midrange tone the old Altec 15" add in the Ampeg cabs so well.
You will have to choose what you like, see if you can get to hear one of those old Mesa 2X15" cabs with EV15L's in them, they sound great, also heavy though.
If you are fit and strong you can get some fantastic sounding old cab's so cheap now.