I like FS2002 for the airports and flight plans etc., but I like CFS2 because whenever you get bored with flying straight and level, you can swoop down and blow something up!

As for running smoother, I couldn't tell you as I have really slow internet and can't really play on-line, so I don't really study framerates. But they both run fine for me.
CFS2 is cool though, you would enjoy it!