I'd get a variable-power Sunpak or Metz Potato masher. They are the most versatile, and the most bang for the buck. The Sunpak 622 in particular is extremely versatile. There are six or seven different heads for it, including an IR head, a zoom head, and a bare bulb head. They have a GN of 200 or so, but are more expensive than the 555.
Sunpak 383 or Vivitar 283 or 285 (all speedlights, not potato mashers) are not bad either, though they have less power. The Viv 283 is not adjustable, which I consider to be a deal killer (though I do have one that I got for cheap).
I decided on the Sunpak 555, which is a potato masher that takes filters and plenty of other accessories, like external batteries, A/C adapters, rechargeable battery packs, etc. It has a GN of 160, and cost me about the same number of U.S. dollars. The filter kit added $30. The only time the flash has failed me was when it got dumped on by a water drop helicopter when shooting a fire. It came back 30 minutes later. It is my #1 flash for weddings, was my number one flash when shooting news events, and I would have no reservations about suggesting one, especially for such mild use. They are very capable and very powerful for what they cost.