i know this will be called but i started with 2 blitzers (only had 2 models) and i like the assassin model so hired one (it was only available as a star player before so only had one model)
The point is i field a team that i like the look of, a dark-elf noble playing BB would have an assassin with him without a doubt. Its the nature of the race! Everyone one else will give you good advice, my advice is select a team that you are confortable with that fits your idea of how they should play. the great joy of BB is there are so many variation in each race.
I have 2 blitzers, 2 W/elves and 2 Assassins now and are 3rd in the league 5 or 6 games in with about the same to go (Buggritt and that Snow troll are second!!) and am enjoying every game.
What ever you decide will be right choice for you (and the dice always roll better for you favourite models, thats a fact!) 
