Retics are cage aggressive most of the time, highly food aggressive, but extremely intelligent. This is true with dwarf and super dwarf retics. Their attitudes have a bad wrap due to the original wild caught lines being so temperamental. But thanks to captive programs, the captive bred specimens are just as workable as their mainland coutnerparts. I will say though, the pure SD are quite flighty and not a lap snake.
As to the OP - if size is not an issue your question is do you want a heavy snake that is going to be fairly calm and lethargic, or do you want a slender LONG snake that is VERY quick and intelligent. If you can work with both then decide do that. It doesn't matter what any of us think, it comes down to personal preference. They both require a ton of respect and care. And their size demands this constantly.