MBP 13'' early 2011 safest OS to go for?

Specs: 2.3 GHz Intel Core i5
8 GB 1333 MHz DDR3
ntel HD Graphics 3000 512 MB
500 gb hard drive, (thinking about going for an ssd)
i use this macbook daily and ive really been looking into upgrading, a new one is out of the question so i discovered open core legacy patcher.