KKB, as noted above, it's hard for anyone to say what would be "best" for you. Some things you might want to consider:
Is flying to one place or another, to begin the cruise, better for you? Baltimore, Boston, New York, New Jersey, Brooklyn?
Smaller ship, larger ship?
Would you like to sail all the way to Montreal or Quebec, or a shorter loop that takes in Boston, Halifax, Saint John, etc.? Are there any ports that you would especially like to visit?
More formal (Cunard) or casual (NCL)?
Length of cruise?