Ergosum :
If you are going to spend money on an M.2, you shouldn't spend it on a SATA is what I'm saying--go with an 850 Evo 2.5." Right now unless you want to break the bank you go with 1080p@144 or 1440p@60--a 1070 won't do 1440p@120 except for esports kinds of games (starcraft) which, professional or not, 144hz doesn't give you a ruddy thing. Shooters/twitch stuff, sure, but Starcraft? Really?
My 1070 drives world of tanks 1080p@120hz, and WoW 1080p@120hz. At 1440 you'll be down in the 70's and 80's.
Starcraft is one of the most intensive reaction based games in the world, you have to macro non-stop (Not macro keys, they're illegal, it's a term), keep track of resources, bases, units and your opponent's forces all while scouting, microing and creating strategies to counter your opponents.
1440p is only 1.6x 1080p, the performance hit won't be that significant.
Watch some master/gm level gameplay from a first person pov and you'll see what I mean, and why 144hz is a must have, and what I have to keep up with.
In regards to SSDs, unless you have a tonne of cash to blow, M.2 is a poor investment for most conventional users, the 850 Evo essentially tops out the SATA connection and will have great speeds.