If you have a gaming PC, the only reason (other than convenience) to have a console is to play exclusive titles.
This is said all the time but I don't necessarily agree. Unless you can run at a higher res than 1080p and 60fps on every game, the advantages of getting multi-plats for PC over PS4/X1 will be nominal at best, at least for the first few years of this gen. People can tout mods all day but most games don't have them, and when they do most of them suck. Bethesda games are the best for mods. I don't have (or need) mods for games I recently bought like Divinity Dragon Commander, The Bureau, and soon to be after i'm finished with those two Saints Row IV and maybe Blacklist. Mods mods mods, it's a legit reason but it's so flimsy. Great for Fallout, Elder Scrolls, but that's all I've used mods on the past few years personally.
Achievements, suspend/resume, having all games under the one umbrella instead of being split into Steam/Origin/Uplay/Bnet, and the convenience are all legit reasons why someone would buy the PS4/X1 multi-plat version over PC. I also can play on our big screen instead of 23" 1080p monitor. Hooking up my pc to the tv isn't reasonable or convenient at all for me. I can't do that, it would be a logistical problem for my setup among other issues like having my keyboard & mouse on the couch with some sort of makeshift flat surface next to me. I also use my pc for school work and I need to be close to the screen for this. The only way I could do this is if we got a second gaming PC used strictly for the big screen tv. I also play mobas
a lot on PC, LoL and Dawngate, I don't know how well I'm gonna be able to last hit sitting 6 to 10 feet away. It's just silly.
For these first years, there will be little benefit to getting PC multi-plats for a lot of people unless you have a monster of a setup that can run at higher than 1080p and 60 fps. If you're just going 1080p like most of us, like the vast majority, then the console advantages above come into play. The biggest reason for PCs besides what I just said a couple sentences ago is cheaper games for PC but that's only if you don't buy day one and if there's a GMG 20% off coupon code out.