Sigma user down Here. I still like the rubi gear though both good choices.
I like the more single action of the sigma seems quicker for me. I hate having to look over the bar to line up marks on tile cuts. I like the handle action.
I like the compact design of the rubi fits in tight places. I also like the way one can line up marks as there is a double bar. I hate the action of the rubi I also hate the handle design.
Once you get use to something just stick with it the more practice you get the better the tool will be for you.