...But when push comes to shove, it all comes down to gameplay.
Video games are, first and foremost, games. Interactivity is the defining feature of the medium. If I want stunning visuals, I'll look at a painting. If I want great music, I'll turn on the radio. If I want a compelling story, I'll read a book. I'm willing to indulge the occasional "art game" that's high on concept and low on gameplay, but for everything else, there had darn well better be a game underneath all those polygons and plot twists.
This stance on video games often puts me at odds with the mainstream. People consistently point to Mega Man 2 as the high point of the Mega Man series, not to mention one of the best platformers in history; I point to the incredible oversights and glaring lack of polish in a few key spots, which can trainwreck the game for even the most experienced players. Star Fox 64 is a beloved classic for many; all I remember about it are fighting with the controls to get my Arwing to do anything more than get shot at, and spending the better part of a day inside Andross' mouth as he repeatedly chewed on my ship in what has to be one of the most unnecessarily long animations in video game history. Final Fantasy III (VI) is continually mentioned in the same breath as Chrono Trigger when people discuss the greatest RPGs of all time; I am continually baffled by how a game with such cookie-cutter random battles and sudden spikes in difficulty can be a contender for such an honor.
Likewise, I find myself enjoying a number of games that the mainstream frequently derides. I consider Super Mario Sunshine and Super Mario 64 to be equally good, but for very different reasons—though 64 is ridiculously fun just to mess around with, let alone play through seriously, the oft-dismissed Sunshine streamlines the movement and camera controls that were so often responsible for the worst parts of 64 (wall-kicking at a weird angle to find the secret room you can't see in the haunted library, anyone?), and the game is much, much prettier (though poke-your-eye-out polygons are charming in their own way). Final Fantasy: Mystic Quest is one of my favorites in the Final Fantasy series because of its simplicity, not despite it—the focus is almost entirely on the straightforward gameplay, which works well for a game that's ostensibly aimed at novices. And I think it's safe to say I'm the only person in history who's rated the Mega Man PC game closer to a 10/10 than a 1/10.
Of course, I'm not always contrary to the mainstream. I'll give you the same glowing reviews about Super Metroid and Portal that anyone else will. My opinion of E.T. The Extra-Terrestrial isn't any higher than yours is. I don't go against the grain for the sake of going against the grain; I call 'em like I see 'em, and sometimes I see exactly what the mainstream sees. More often, though, the mainstream and I look at games from different distances, at different angles, so my perspective usually sounds a little skewed by comparison. Doesn't matter if I'm right or wrong—as though "right" and "wrong" truly apply where opinion is involved—I think it's important to have a dissenting opinion now and then. If there's enough of a majority for there to be a mainstream in the first place, I'd rather it be because a bunch of gamers came to the same conclusion about a game after really thinking about it, than because a few particularly vocal individuals shaped the opinions of countless others who aren't so discerning, analytical, or opinionated.