Carl gives good advice. If you tow often, a big block engine will provide better performance and economy too. If towing is an occasional weekend thing, then maybe a smaller engine will do better overall, even though it gets poor mileage when towing. The other thing you want for good towing is a relatively high rear axle ratio, probably in the 3.73-4.10 range. That's not an "economy" axle.
You can probably tow with a 1/2 ton truck (F150/1500) but you are near the upper limit of its towing capacity. Again, if you tow only occasionally, that may be the better choice, but if you tow frequently or long distances the 3/4 ton (F250/2500) models will do better.
As for which brand, it's pretty much a matter of personal preference. Ford, Chevy & Dodge all make excellent trucks these days and their drive trains are solid too. Just don't opt for one of the small engines, e.g. a V6, on the assumption is it more economical because chances are it is not on an overall basis. You can view the towing capacity for various trucks online - each manufacturer has a spec page that shows max towing capacity by model/engine/axle configuration. Pick one that covvers your rigs weight with some extra Head room, per Carl's suggestion.
This page, for example, shows all the towing capacities for a 2005 Ford F150: http://www.fordf150.net/specs/05f150.php
You need to be concerned with the towing limits and the GCWR (Gross Combined Weight Rating). If you are not familair with terms like GCWR and GVWR, see the RV Glossary which can be found via this sites home page (www.rvforum.net).