I've been using macs since 2004.
And i think their os was great up to snow leopard, everything that came after that, was just full of bells and whistles trying to make their computers work like an iphone or ipad. I had problems when installing new software or running old stuff ever since.
Im currently running mavericks, it seems to work fine or better than mountain lion to me, yet when it comes to install drivers for peripherals is nothing but headaches. In fact, installing a canon selphy printer a couple of weeks ago, involved in going to terminal and changing lines in the installer script...WTF? it was like a windows 95 sort of experience. I will personally stay away from any osx upgrade until all the software i need for work works fine.
Im using a MBP 15" i7 mid 2010 or 2011 with 8g ram, OWC SSD.