We’ve said it before and we’ll say it again: Boston has some fierce burgers. Now we can add a few more to the mix. Zagat Buzz recently pit newcomer Tasty Burger against the heavy hitters. Also carving out a steady hold, Virginia native Five Guys may prove a worthy contender as they step up their presence with a slated opening in Framingham (making it the Hub's 9th outpost) and find favor with the local press. Add New York's 5 Napkin Burger, which is destined for the Prudential Center, and the forthcoming Art of Burger on Commonwealth Ave, and it looks like burger lovers will a steady supply of fresh meat to critique.