Lawsuperstar -
First, how did you manage to do so well at Suffolk? Did you use mostly commercial study aides (e.g. E&E and Gilberts) or did you mostly stick to briefing and reading the cases? Can you offer any other advice on how to succeed at Suffolk?
Second (like LawGirl), I have done a lot of research on the schools in Boston and I will try to answer your questions:
I honestly think that you are going to have ample great job opportunities coming out of Suffolk with your class rank, and I'm not sure how much transferring to BC or BU will increase these opportunities. If you're in the top 1% at Suffolk, it could be risky to transfer to BC/BU, because if you end up in the bottom 50 %, for example, you could be worse off. However, since you were able to do extremely well at Suffolk, I'm sure you'll do well at BC/BU. I'd say that you'd have to place in the top 25% at BC or BU to increase your current potential for employment opportunities.
It also depends what you want to do and where you want to practice after graduation. I'm assuming you want to go into BigLaw, since you want to transfer to BC/BU. If you want to practice BigLaw in Boston, you'll be fine at any of these three schools. However, if you want to practice outside of Boston (DC, NY, anywhere else), don't stay at Suffolk -- go to BC/BU.
You also want to think about whether you want to leave all the people you have met at Suffolk (friends, etc.) because you'll have to meet new people all over again at BC/BU.
That said, if I were in your shoes, I would probably go to BC. Despite the rankings (BU - 20, BC - 27), BC is still king in Boston (I plan on practicing in Boston). It's second only to Harvard, and most of Harvard's grads do not practice in Boston.
If you're looking to practice outside of Boston, then BU would probably be a better choice than BC (BU places better nationally). These differences in reputation in Boston vs. the rest of the country are not huge, however. Therefore, it is also important to look at other aspects of the schools, such as location, facilities, academic programs, etc. I like BC's location better, because it's not right in the middle of the city. If you like the city more, go to BU. I also like BC's facilities. BU's are supposed to be pretty dumpy.
I have just been accepted as a transfer student to both Boston College and Boston University. I finished my first year at Suffolk as #4 in my class. I have been offered a scholarship from Suffolk, probably to entice me to stay, but I really think that I need to transfer out. I have insignificant personal reasons for wanting to go to BC, but would be happy at either BC or BU. I would like some advice in deciding between BC and BU. I know that BU (20) is higher ranked than BC (27), but does that really matter? Also, am I making a mistake by not accepting the scholarship and remaining in the top 5% of my class at Suffolk? Any advice and opinions would be greatly appreciated.