The question should not be whether or not the Pats could use an upgrade over Branch; of course they would like that.
The pertinent question is at what position do the Pats most need to upgrade?
Are we really more comfortable with Arrington, Moore, and Dowling/McCourty at corner than with Welker and Branch or whomever his replacement may be at wide receiver?
Are we really more comfortable with Chung, Ihedigbo and McCourty/Dowling at safety than with Welker and Branch at wide receiver?
Same deal at OLB and DE; if you could only pick one, what position would you want the team to upgrade?
Whatever it is, that's your number one priority.
In my opinion it is not wide receiver.