Some very general information...
Take a look at this chart:
http://www.diefenbacher.com/Sweeps.htm
You can make a case for various combinations. Given only 3 to carve a bowl, I would like to have a big low sweep (I have a #3-30mm) for smoothing, something a little narrower and deeper for a lot of the hogging, maybe in the #6 to #8 range and somewhere between 16 and 24 mm and one #8 or greater that was 10 mm or less. You could carve an entire bowl with any of those, but three are things each is better at. I like straight prfiles, but mostly due to getting used to what I have.