Well, the first thing you need to know is how to tell your bandmate to **** off. You don't tell him what kind of strings he should use, do you? If you liked light strings, that's what you should be using.
Secondly, string preference is a very subjective thing. What I like and what you like could be completely different. That said, I think the Ernie Ball's were probably a good place to start, maybe try GHS Bass Boomers, DR's, and maybe D'addario's. Trying those out should give you some basis to develop your own personal preference. Once you figure out something you like about a certain string, you can base your next string purchse on that.
For example, lets say you try some nickel D'addario's, and then some stainless DR's. For the sake of argument, let's say you like the DR's better. Now you can pretty safely assume that you like stainless strings, and then you can base your future string purchases on that.
If you have any other questions, don't hesitate to ask. Pretty big wealth of knowledge on here, happy to help
