This question...
... is pretty hard to answer. A lot depends on the wind conditions where you sail (Long Island Sound?). On the Chesapeake, for example, we have notoriously light winds in mid-summer (fondly called the "doldrums" here). As a result, I bought a 150 furling genoa for my Hunter 28.5 and have been very happy with it. This sail is great for my boat in winds up to 15-16 kts or so. At that point, I've to either reef the main or furl the genoa -- and I usually choose the latter since it's easier and I single hand the boat a lot. I've also found that with leech and foot control lines, and a foam luff, I can furl/reef the 150 headsail much further than the common belief that anything more than a 30 per cent furl will degrade performance. Not only does the boat sail very well with a tightly furled headsail (sometimes up to 50 per cent furled), but performance is not what you're looking for when cruising in rising winds anyway.Having said all this, a 135 is a very common and popular headsail and would probably be somewhat less expensive and would work pretty well in most conditions. So in addition to cost, the only other major consideration IMHO would be just how much you want to sqeeze out of your boat when the winds are really thin.