Generally in rodents, the males are the more relaxed and easygoing. Male rats do tend to be more like lapdogs, content to simply sit with you. Females are a bit more energetic, eager to explore. However, it does depend on each animal's individual personality. Both genders make spectacular pets, it's just your personal preference and which personalities from the selection of rats appeals most.
I personally keep my rats on lab blocks/pellets, as they seem fond of picking through a seed mixture and eating only specific bits of it (it can make for a less complete diet). However, if you choose a seed mixture, you can make up for any missed nutrients by adding Quacker Oats dry oats into the food, offering the occassional bit of Romaine lettuce, hardboiled egg white, mealworms, and crickets (the last three are important, as little protein is available in the seeds).
And bravo for deciding on two rats. They social animals are need the companionship. They'll still bond strongly to you, but they'll also have a snuggle buddy when you're not around to play with them. Good luck with your new friends to be!
Rodent manager of a pet shop, owner of three rats