Its difficult to say, not knowing your fitness level or riding style but I have been using a Stronglight Z-Light compact double 34-48 with a shimano 9 speed 12-25 cassette and it gives me a good range of gears, not too much overlap, with some nice low gears as well. I'm 80kg's and like to ride at about 90rpm and it works good for me.
One real advantage is there isn't that loss of face when you drop it into the granny gear.....cos nobody knows you are on a compact!
Also means a shorter chain, lighter chainset and all round simpler setup than a triple. However I do have a triple on my pure training/touring bike and it works fine as well.