Safari for me. It is a silly quirk, but my favorite feature of Safari is each of the "tool bar" bookmarks is listed with a number. First one on the left is number one, so you can click "Command + 1" and it will go straight to that site. "Command + 2" goes to the next one over, etc... Of course, RWG is my #1 bookmark
It's just nice to type as little as possible sometimes. Another quirk of mine is is with Safari, if you hit "Command + L" to load a page, and start typing something, it autofills based on sites you go to the most. Firefox does this as well, but it gives you a list which you have to scroll through to select the page. I don't have time for that sort of thing. I want to hit "Command + L" and start type rw.... and then the rest of the site name is filled out and I just hit enter. I don't have to mouse down, or use the arrow buttons down to get to the page I want. Too many steps I try to use the keyboard as little as possible and the mouse even less.