I personally prefer ballheads for speed and convenience. I had a cheap pan-and-tilt head once and struggled with it, and never got used to it, although many say its a matter of getting used to it. I've heard that pan-and-tilt heads are better for macro photography and the like, but since I almost never do that, life has become cheerier since the purchase of my ballhead.

If you do decide to go with a ballhead, do find one that is the appropriate size and weight for your equipment, particularly if you have heavy lenses. It's usually a compromise between ballhead weight (some weigh a tonne) and the weight of gear it can support. I use a Markins ballhead after reading rave reviews about it on the Nikonians website, and I certainly have nothing but good things to say about it. It is fully compatible with the Swiss-Arca system and its plates. Check out the Nikonians website for more extensive reviews on this ballhead, but I have no complaints! I used a cheaper Manfrotto 438RC ballhead before but got rid of it after I found it a little clumsy with vertical compositions.

Your mileage may vary, good luck.
Jin