If the new Mac must be a laptop and screen size is of paramount importance, a 15" MacBook Pro is your friend's only alternative. I'll qualify that, though, by saying that because of their much improved screen resolution, the new 13" models have satisfied people who thought they couldn't live without larger screens.
But be advised that regardless of which
new machine he buys it will be 6 incarnations of OS X/macOS removed from Snow Leopard, and there will be an awful lot of catching up for him to do.
On the other hand, if he's not up to the "learning experience" he may be best off buying a used or refurbished MBP that can run Snowy.
(A laptop with a free-standing keyboard and mouse?
)
