I think it's best just to stick to the pre-Crisis Legion. It's easier to follow because that's the one with the longest uninterrupted history (1959 to 1991).
The appeal to me of LSH as a kid was the sheer number of heroes you got in there, and Levitz and Giffen did a superb job of making me care for most every single one and making each one distinct. I also got a thing for comics with long histories and that acknowledge that history.