the Bayou Classics are always a good and popular choice. I have the SP10 and love it. Another popular (but a bit more expensive) burner is the Bayou Classic KAB4.
These are both high pressure burners (150,000 + BTU's).
It really depends on your setup and how big your batches are going to be. If you would like the ability to do 10 gallon boils, I would suggest a high pressure burner like the ones above.
FYI, a common keg (keggle) does not quite fit on the SP10, I have to lay my bbq grate over the top of it, then my keggle on top of that. Other burners have the diameter to hold a keggle better.