I have some doubts and i need ppl here to help me out in it ?

How does one determine what routing protocol to use in an environment ? I am actually biased towards RIP as i believe that is the most used protocol in a very general business environment. ( but m not sure )

Secondly, How do we determie which router series is apt for a particular environment ? ( I believe 2500 series is widely used )

DO we have any ruleset to determine both these questions ? Or is it just a gut feeling ?

Thanks