I'm a big PC player myself, generally the games I really like are best on it or only on it such as STALKER, Metro, most Bethesda stuff, but there can be good games on consoles for sure. Not everything is on Steam, though most of it ends up being on there and it is a really great platform. There is the downside though of ports that get that shit treatment on PC. There's a lot of those games that are just terrible on PC. Mass Effect 1, Borderlands 1, the initial Resident Evil 4 port, Dead Space 1, these are not PC recommended titles.
Most everything has good exclusives on it. The PS3 does, the 360 does, the Wii U does, the Wii does, there is always something good. I understand the convenience for sure, I have a massive Steam library, though I am starting to pull back on the digital releases I can unless they are stupid crazy sales and anything in the future that is new that I want will be a physical copy for myself that will most likely end up being steam anyways, but I want more physical titles.
Just on PS3 alone, there's the PSN network that is gonna have the PS1 games, there's HD ports of Shadow of the Colossus, Jak & Daxter, Sly Cooper, there's good games like the Uncharted Series, God of War series, 3D Dot Game Heroes which is basically a Zelda ripoff/tribute, and others like Ni No Kuni that I'll recommend on it being Studio Ghibli related alone as I still need to play it lol
I feel like the 360 is a tad lesser in the exclusives department, even if I was a supporter of it during the generation.
It kinda comes down to...What games does he like? Does he likes shooters? They are the best on PC hands down. Does he want platformers? Generally better on consoles, but there are alot more showing up now on PC with the big 2D indie platformer push. Action games? Generally better on consoles especially when the ports don't really bring much. Racing is better on consoles, though Sega All Stars Transformed is great on PC. RPG's? Basically just consoles for the most part.