letting n00b - should i join RLA or NLA?

I would appreciate some advice on joining either of these organisations.

I think as far as forms and advice they're similar, from what i can see.

My landlord's insurance is up for renewal and i think i can probably beat the renewal quotation of £344.

I believe that both these organisations offer discount, bu i cant get accurate quotes until i sign up :(

any help would be great! thanks!