As far as raw speed is concerned, the Samsung EVO is the way to go. The drives themselves are very reliable and have the faster read (540mb/s) and write (520mb/s) speeds.
I myself have a Samsung EVO and it works flawlessly in my PC. In my PS4... well I haven't tried it in there.
Some people claim its a bad idea, and that you won't see any difference in speed with the use of an SSD due to hardware limitations of the PS4; they claim that an SSHD is a better call for this sort of upgrade. You can read about that here.
On the other hand, this gentlemen here saw a large difference in speed with some games (check out the tables he created with load time comparisons).
My advice would be: if you see value in the upgrade to an SSD based on the sources I've provided, go for it.
If you were expecting an SSD to cut your load times in half across the board, either temper your expectations, or save some money and get yourself an SSHD.