alien bee or westcott
If your looking to stay with Westcott, their Strobolites uses the bowens mounts, so for starting out you can buy strobolites and then later on upgrade your strobes to Bowens lights. Ive rented the Bowens system before for jobs and love the simplicity and ruggedness of them (way more then my Einsteins).
One reason to stay with the Bowens mount is the future upcoming Westcott LED light that Scott Kelby has tested out. Which ill probably pick up for video work. (under 100 watts, but puts out 1000w tungsten equivalent and in Bowens mount). If I had to do it again id pass on my Bee's (although I like my Einsteins), and build up my setup for a mix of video and stills (probably with Profoto, Bron or Bowens). Thats the one sucky thing about Alien Bees, no continuous light options for the terrible AlienBee mounts. And no plans from Buff to make any either
Take any advice given on a forum with a grain a salt. (that includes mine). Nobody is perfect, though many claim to be.