I don't think it will be too hard to decide between 4 because it's unlikely you'll like all equally. You'll probably get a "feel" for one or two of them that you're really drawn too and from there you can start narrowing it down. Right now if they've met the primary criteria which they have cos you decided to contact them to find out more... the see if they meet the outside contact, what kind of support etc and if you're happy with that then the next thing you're looking for is a "feel" for them, are you drawn to any personality wise etc.