I have had both 105 and Sram Force shifters and derailleurs on my bike and either will work just as well. I have learned to like the double tap on the SRAM. The SRAM upshifts with a very small tap and downshifts with about the same amount of movement as a 105. I love the cable routing and if the new 105s route next to the bar it is a big improvement. I still use Ultegra Cranks and switch between SRAM and Shimano cassettes depending on the wheels I am using. I like both setups but for me the coin toss goes to the double tap for shifting from the drops. My back up road bike is Shimano but I have been thinking of upgrading to a 10 speed and I am in the same boat between Rival and 105 as you.