My employer is giving me a Blackberry. I have a choice of three models:

8700
7130
8100 (Pearl)

Which should I go for?

I'll be using it mainly for email, and occasionally as a phone.

I'm unlikely to use it for GTD - my plan is to stick with my Treo 650 for that (basically the Treo is my personal phone, but is sync'd with my work computer - I use Agendus for GTD and I get on with it very well).