I chuckle to myself a little bit every time this question gets posted. I don't chuckle at the poster, I think it's great that new people get on and ask and I think it's a legit question. I laugh because every time three things happen: People say "I prefer {blank}," someone directs to PullMyFinger, someone says "Get whichever one you like most." Granted, they are all three very realistic things to respond with, I just get a chuckle every time.
That being said, no one has gone the last option, so I will. Get whichever one you like the most. Be aware of the extra models you will need, be aware that some masters have a pretty high learning curve, and be aware how you want to play. I personally buy models I want to paint, then struggle to get my mind around how they work.
Another option is to get in touch with the Henchman in your area, see if they will let you use one of their demo crews(they will... they have to... and likely want to) and see which one you like best out of their crews. That saves you the investment of going for something you aren't ultimately happy with or might open your eyes to a crew you hadn't thought of yet.