Fun to shoot, AND small enough to carry...
Well, my favorite carry 9mm is a Kel-Tec PF9, with a belt clip. It is really lightweight (about 12 oz). I wouldn't rate it as a "fun gun", though. It's a no bullshit, defensive piece, can carry inside waistband, nobody knows it's there, even when I just have a t-shirt and jeans on.
Fun to shoot? I have a P6 that has been tuned up, (short trigger, short reset kit, wolff springs) it's a hoot to shoot. I put thin grips on it, made it as thin as possible. But, it's two and a half times the weight, up around 29 oz.
I carry it outside waistband, but only when I've got a jacket that will conceal it well.
I recently shot a Stoeger 9mm, and it was sweet. Felt good in the grip, loved the trigger, and target re-acquisition was quick. It belonged to a friend of mine...I have a feeling I will probably own one sooner than later.
If you haven't done it yet, get down to the ranges and check out some rental 9mm, might help you fine tune your decision.