It really bugs me that Yosemite, and Yosemite Safari in particular, enforces center-aligned everything. I like the links in my bookmarks bar to be left-justified, and the url in the address bar left-justified. I also like my tabs to be one size (regardless of how many are open) and left-justified. Safari has slowly broken all of this; Glims allows some of it to be restored (like tab length and orientation) but the url thing in particular really bugs me and I haven't gotten used to it. To copy part of a url, you click on it and watch it slide away from you over to the left. It's maddening. (I also used to pin my dock to the left corner in OSX, but the command line pref setting to enable that has also stopped working in 10.10). I don't understand the basis for enforcing those choices, so I'm forced to think it's an aesthetic preference of Jony Ive's (or whomever), which is extra bothersome.
Browser-wise, I would use Chrome (and do for development) but the handoff and airdrop features that now work quite well between Mac and iPhone keep me using Safari on both platforms.