I think both procedures are safe, and have great benefits. Here are a couple of questions my surgeon asked me when I couldn't decide. Do you have GERD (acid reflux)? If you have moderate to severe reflux then RNY is better, as there is more reflux with the sleeve. Do you take NSAIDs on a regular basis (Ibuprofen, Alleve, etc)? If so, the the sleeve is a better option, because you will not be allowed NSAIDs after RNY. Do you have diabetes? If so, then RNY has long term research regarding its role with diabetes (although I fully expect this will change as the results from ongoing studies with the sleeve are published).
It was very hard for me to decide, but I ended up choosing RNY because my blood sugars were creeping up, along with a very strong family history of diabetes. Whatever you decide, make sure you talk to your surgeon in depth. Good luck!