Depends on what you have to spend. You'll be hard-pressed if you don't want to spend more than either of the next-gen consoles, largely because optimization for PC ports can be so spotty. That said, my PC is now 1 year old, and when I built it, it was largely low-mid range specs and cost me under $1000 so I figure it can be done. I don't foresee needing to upgrade for at least another year, and then, only if I really care about playing games on max settings(and that upgrade could foreseeably last the rest of next gen). The biggest benefit to gaming on a conventional TV is that the resolutions are currently capped at 1080p for most people(lag could be an issue).
With all of the talk of the multimedia capabilities of Rokus and AppleTVs and the new consoles, I often find myself wondering what all the hoopla is about since I have my PC hooked up directly to my TV. I have no issues playing any media on it, obviously, which is a big step-up from pretty much any of the other options. The versatility of the PC setup is unrivalled.
Obviously the biggest drawback is the need for a KB+M, which can be somewhat solved by various wireless solutions. It really hasn't dampened my enthusiasm for this kind of setup. Most third party games these days eventually, if not simultaneously, see releases on PC. So, you'd only miss out on the occasional exclusive. I think the only exclusive console games that have come out this year that I cared about were Ni No Kuni and The Last of Us. If you are a sports fan, the only games that come out for PC anymore are NBA 2K, FIFA, and PES that I can think of. The options for indie/smaller games are much greater than you'll currently find on the consoles, and I don't really see that changing.
I'll be completely honest here. Getting back into PC gaming was the best gaming decision I've made this gen. I've enjoyed this last year with my PC more than I ever enjoyed my 360 or PS3(and Wii U). I can easily browse the internet, stream movies, play games, and do other stuff(read: porn). I think the only genre of gaming that I'm really missing on the PC is a solid sim-ish racer like Forza or GT that offers a solid career mode progression, but Assetto Corsa and Project Cars will hopefully remedy that.
Edit: I should mention that form-factor is also a drawback. My PC has wires out the wahzoo and serves as a nice block heater. It isn't really any louder than my 360, and when I'm gaming/watching a movie, I can't hear it at all. I would add that your experience will differ based on your own level of experience with tech/PCs overall. I would imagine that, as easy as it might seem, a lot of people in the general public are still rather clueless about these kind of things. But if you're at all competent with tech, I don't think you would be disappointed to go this route.