In order of speed ranking:
1. Samsung 850 PRO
2. Sandisk Extreme PRO
3. OCZ Vector 150
4. Sandisk Extreme 2
5. Samsung 850 EVO
All of these are very close in performance so you would probably never notice speed difference. Choose one based on brand reliability and warranty.
http://www.fastestssd.com/featured/ssd-rankings-the-fastest-solid-state-drives/