Keep in mind with Metal Gear that you need to play the games in order of release, not chronologically. It’s sort of a Star Wars prequels situation where the prequels spoil the sequels.
Here’s the proper order to play them in:
1 - 2 - 3 - 4 - Peace Walker - V
Yes yes yes yes!
I’d argue that you can probably go 1 - 2 - 4 - 3 - Peace Walker - V (so, do the Solid Snake games first, then the Big Boss flashback games last), though 4 will spoil some of 3. But Peace Walker is very much a direct sequel to 3, so … *shrug*
(We don’t talk about Portable Ops.)
Oh, and it should go without saying that you play MGSV: Ground Zeroes before MGSV: The Phantom Pain, but you can buy both in one package now (both on the same disc), so that might now be moot point.