Hideo Kojima suggests newbies begin with Metal Gear Solid 3
Speaking on Twitter, Kojima said after you finish MGS3, you should move straight into Metal Gear Solid 4. His reasoning: the more modern controls.
“I often get asked ‘which title one should play if haven’t done MGS series?’. Play MGS3 as control is more modern, if you liked it then MGS4,” he said. “MGS1+2 has [a] camera [with a] bird-eye view. If you want to learn the story, then just read the novels [included in the Legacy Collection].
“When the concept of the Legacy Collection was brought [up at a sales team meeting], the development side stated that it’d be hard for current users to play MGS1. Since it’s a bird-eye view, you can’t really see the front side which makes it hard to self-adjust for someone accustomed to FPS/TPS.
“I’d suggest [Peace Walker] for younger gen, but it’s hard to play solo unless you do co-op [with] PSP online. Hard boss battle if you like to take [the] time and play.”