The southern route is obviously a lot longer than northern. I really know bugger all about the Atlantic other than what I read but if you chose the Northern route what time of year is best ?
Also, wouldn't the sail north along the US east coast tend to be a hard slog ?
It is all to do with the Azores high and the trade wind belt. The best time is April May when the belt should be well North. If It is delivery it might be possible to skirt just North of the Canaries and head across for about 2000 miles before heading towards Bermuda. From Bermuda to the NE USA you 'should' be in SWs.
The Northerly route is a non starter unless you can motor most of the way.