Marshall are a pretty good deal if you can get a used one, i think $749 is A LOT to pay for a new one with gt-75's (and it's like $100-150 more if you want vintage 30's!) they're generally $300-400 used (i scored mine for $250 with a bad speaker that cost me $75 to replace...so i still came out alright)
Mesa are as top notch as they come, but again $849 new is pretty steep...but their construction is far superior to marshall's so you do get a better cab for the cash...sometimes you can find them used in the $500-600 range
I really like the new randall cabs with vintage 30's, the XL cab i tried with my cobra really sounded good...they've recently upped their prices as well, but if you shop you can find some killer used deals; these are very similar in sound and quality to the mesa cabs
might wanna check out splawn cabs too (
www.splawnguitars.com ) $699 for a new cab with your choice of eminence, $799 for your choice of celestions...your choice of tolex, and grille cloth...they're not cheap, but they're built like tanks and sound killer (i chose mine over a bogner uberkab, partially due to the price, but i don't regret it a bit)
Rivera, Orange, and Bogner have some really great sounding cabs (i think pretty much anyone would agree) but they are pricey