I wouldn't really recommend KotoR as a beginner option on PC just because of how fucked it can be on modern PCs. Resolution patcher takes a bit to get running and even when it's working the UI when in menus is tiny as fuck, and alt-tab tends to result in half of a black screen after the second alt-tab, at least for me.
I'm doing a replay of it now so I can do KotoR2 without missing out on anything since it's been at least 14 years since I last played the game, but christ the writing is actually pretty shit and there are some fucked up design choices, like having Jawas milling around ten feet from groups of sand people who want to enslave them or having people exhibit no reaction to you stealing from them, or admitting to trying to help the sand people while buying the vaporators from the guy in the very same room as the woman who just told you quite firmly that the big bad mega corp has no interest in a peaceful solution also provoking absolutely no reaction.
I mean older RPGs definitely have some level of jank but this is all shit that might bug the hell out of this friend of yours. And depending on how much tweaking he's had to do to get his previous games up and running, he might not enjoy having to set it all up for KotoR either. But then again depending on how much of a Star Wars fan he is, maybe he'd be willing to look past it. KotoR1 is basically a proto-Mass Effect anyways if you look at it in a certain light.
I would go with DA:O over KotoR1, personally, though it's not the greatest option. More suited for modern systems, though as I recall there was still a crashing bug in the PC version during that Fade quest in the mage tower or whatever. New Vegas is a better option, but if you are dead-set against it because FPS or whatever...
Ah, right, it took a minute to think of it, but Alpha Protocol is also a pretty good option. Plays like Mass Effect but with significantly more C&C, and I don't recall any gamebreaking bugs in my playthrough other than the occasional load despawning enemies.
This'll get me a few Shit ratings too, but Dragon's Dogma or Dark Souls. They're more action than RPG, true, but if your friend is more used to action and sci-fi environments rather than fantasy, they might be good starters for that genre. Besides, they both easily beat Skyrim!
Oh, one last thing. It's hardly mentioned here, likely because it's more of a JRPG, but what about Septerra Core?