Yes for a cross platform title, where it is ported to each platform with some bare minimum of competence, the best *potential* PC gaming experience - just in terms of modability and graphics - is far superior to the optimal experience of any console. It may even be true - and it is for some games - to say that of the *average or better* PC experience. As a long time PC gamer who has owned several consoles, including the PS3 and Xbox 360 most recently, I have to emphasize that as only being true across a subset of the range of experiences. This is not just because there is more variability in PC hardware capability and so the optimal experience on a given setup can be significantly different from the best possible experience, but also because the actual experience on a given setup is sometimes far from what should be optimal.
This is particularly true for any gamer who has a PC they would tentatively call mid-range in terms of performance capabilities (for reference my $600 heavily discounted Core i7 3770k with Radeon 7770 would fall into this category due to the middling radeon 7770.) It is here where users may find they are able to run some new games at maximum or near maximum settings flawlessly while the default settings of a few games yields terrible slide-show performance. More often than not having the power to run it at the resolution they want and acheive the visual fidelity they expect appropriate to their system's capabilities, this is a matter of features being used being ill-supoprted by or espescially taxing on their hardware. It is then that tweaking settings, sometimes using Nvidia or ATI tools or editing INI files, becomes the price of getting the experience that your system is capable of. Users who can not be bothered must settle for either lower fidelity than their systems can reasonably produce or worse performance. That there is no "mid-range" of performance or feature sets (or DX feature levels) to run afoul of inappropriate default/automatic settings for console users to have to worry about can not be understated. That a console gamer can *generally* be assured that they are having the optimal experience in this sense should not be undersold - even if a game is crap at least a on a console you know that it's probably just as crap for everyone else as it is for you.
For me, I don't mind the tinkering and actually kind of enjoy figuring things out in cases where games (Skyrim on my system at launch for example) run far worse than they should. At the same time I know the possible frustration well enough (Skyrim 4 days after launch on my system at the time for example) that I can't really see judging someone for how they weigh the costs and benefits in this matter. So I don't think one can flatly hand it to PC gaming based on performance and presentation. I'd say that in that regard it's really a matter of individual preferences and tradeoffs; often the choice seems obvious for the individual but neither the weights nor the apaprent obviousness of the balance should be presumed in any way universal.
I think the only unequivocal advantage that PC gaming provides is that it has some semblance of a competitive marketplace. I mean that you have a number of content delivery services vying for usershare; Battle-Net, Steam, Origin, Amazon, GoG.com, Desura, The Humble Store, U-Play, etc. Now anyone familiar with more than one of these services can immediately point out some of the flaws in this marketplace - most big titles are exclusive to either Steam of a publisher's own service like Origin or Battle-Net. Additionally, some services like the Humble Store or Amazon don't serve all or even most of the content themselves but once again rely on the publisher's services or Steam.
It's fair to say then that whatever competition there is, it's not as much over who can provide a specific game at the best price and with the best customer experience. None of the other services are competing with Blizzard to offer better prices and a better experience purchasing and downloading Diablo III obviously. In this way the PC marketplace is far from ideal, in terms of consumers being served by competition to the extent that one might imagine.
There are several real competitions going on though that do benefit PC gaming consumers quite a bit. Steam and Origin, and to a lesser extent services like Uplay's store, are in competition over the install base and engagement of their customers. While it may seem one sidedly going in Steam's favor, the emergence of publisher-owned content delivery networks has kept Steam on its toes and it strives to maintain hegemony by both keeping customers engaged and making itself valuable enough to other developers/publishers that they do not see creating their own services as worthwhile. At the same time, services like Origin actively strive to justify themselves in the face of Steam. While I still question the worth of the service in comparison to Steam, EA's commitment to it has prompted them to offer periodic significant sales and I believe was their impetus behind participating in a 100%-to-charity humble bundle (to attract users to Origin.)
A purer form of competition exists on the indie level where games will be offered simultaneously across multiple services and served by each of those content networks directly instead of as a voucher for Steam. GoG for example had gradually improved its accessibility to smaller indie titles and become quite a popular service-of-choice among Kickstarter backers. This in turn has driven Steam to make their service more attractive and accessible to quality indie titles, though whether or not the execution of such programs as Greenlight hit the mark is another topic for debate.
Piracy also plays a role here as content providers in the PC space are much more acutely aware that they are also in competition with the pirates. To some degree at least they almost all realize they have to offer something the pirates can't. While I think Blizzard and EA have made miscalculations in how they have dealt with this realization, Steam and GoG have not. They both realize that the best way to compete with pirates is to try to offer a better service and experience where possible - though GoG's view brings them to the conclusion of forswearing all DRM while the reality of Steam's dual service to both publishers and consumers requires more of a balancing act.
http://www.eurogamer.net/articles/2011-10-24-newell-stop-piracy-by-offering-superior-service
http://www.escapistmagazine.com/news/view/126015-Good-Old-Games-Pirates-Are-Our-Competition-Not-Steam
I think why these sorts of competitions matter and are of as significant a boon to PC gamers as they are is because they are interchangeable in one way that services offered by/for specific consoles are not. While, even more so than consoles, games can be exclusive to one service the services are not exclusive to hardware. That is to say that Steam has to care about users spending time, money, and attention on other services because there is no hardware-purchase barrier to them doing so. They might not be competing with many of the same products, but they are competing over the same wallets and there's nothing to stop most of those users from spending it wherever they want besides grabbing their attention and offering them a reason to spend it with your service first.
Hopefully what Sony is doing with Amazon in terms of allowing them into their ecosystem may produce at least the same sort of imperfect and incomplete competition which benefits PC gamers. Sure PC Gamers like me will lose the one true advantage I think our platform of choice has, but I'd trade any imagined bragging rights over one more platform where the market works slightly better for consumers than it does now. Besides it's not like the market works perfectly in the PC gaming realm, so anything that makes Steam and various PC services feel like they have to improve even a little bit more would be welcomed.
