Agree with FuzzyWuzzy. The feel of the Shimano hoods are better compared to Sram. And for the shifting, do you want one shifting movement or two?
IF I were to build another bike I would definitely go for Shimano as the shifting performance is a lot smoother.
Try and have a go on both if you can to see which you prefer.
Edit; opinions base on Sram Rival verses Shimano Ultegra.

