After thinking about game review sites and discussing some AAA games with my friends, the comparison x game is better than y game is frequently used. What I believe is that no game is truly better than another. Here are my main reasons why I believe this:

1. Target Audiences: Oftentimes you find a game that seems too childish or too difficult or involved for you, so you quit and and don't regard that game as a good one. This is a false acquisition because you may have not fitted well into the target audience. Some games appeal to very wide audiences, but that doesn't necessarily mean it is a better game than another.
   
2. In the Moment: This is an interesting factor easily seen while listening to music. Sometimes a song, artist or even genre only appeals to you while you are in the right mood. If you aren't in that mood it is extremely annoying and you have to listen something different or nothing at all even. Games are much the same way. Sometimes retro/arcade games are only played for nostalgic reasons, not necessarily because the game was particularly well designed or entertaining.
   
3. Some things cannot be compared: This is like comparing a RTS to a FPS: they are fundamentally different, and generally share completely different pacing and mechanics. Same with comparing a techno song to a classical song-they are too different.
   
4. Human Error: The human being is such an immensely complex being--the only one you can come close to understanding is yourself. Things like a person's childhood or family background can greatly influence their opinions of a certain experience, making it impossible to judge whether or not another person would appreciate the experience the same.
   

So, how do we know which games are worth playing and which are best left alone? I think there is one determining factor that can be considered: Quality. This includes the quality of presentation, the quality of technological design, and the quality of the game design (as in the balance of mechanics, challenge, flow, the synergy of the entire game, etc.). Quality is what separates the twelve-year-old home developers from large 200 person teams or learned indie teams.

Even quality isn't perfect for judging two games. Just because a roguelike has poor aesthetic appeal doesn't mean it's worse than Skyrim.

What do you guys think of this theory?

While there are no games that are excellent for everyone there surely are many games that are terrible for everyone. Buggy, ugly, slow tetris clone with broken controls is terrible no matter how much you like teris and what mood you are in.

You're right, no game ever made is better than Big Rigs: Over the Road Racing.

Priority is delegated by the audience, specifically those with discriminating tastes. Meta critic is a great example of prioritizing based on the general population. Its only worth as much as you are willing to say its worth. I think its safe to say that most people have a handful of games that are in the +80 meta critic range that they hate or an under -20 range that they love with all their heart.

Very true. I was thinking more about Meta critic. How I think they could do their ratings is if there was anything intruding on the gameplay (like Acharis said with the tetris clones). If the game quits every 10 minutes due to some breaking bug, it's not a "good game".

I want to add: while many may disagree why a particular game is good, most of us would agree on why a particular game is bad. And even if the game is bad, sometimes it still entertains you. For me, this was Hellgate London. I agreed with the many people criticizing it, it had issues. But it somehow still entertained me. Comparing Diablo 2 to Hellgate, Diablo was and still is the better game. Better artwork, more interesting mechanics (with the synergies from v 1.1x) and even a better story, that was better told. That doesn't mean Hellgate London didn't entertain me.

Comparing games is like comparing movies in some aspects. You can compare the story, story progression, artwork and distinctive artstlye, Gameplay mechanics and the community supporting the game. To some extend, you can also compare the atmosphere and the overall quality of the game.
This brings me back to the movies, I would never say that Expendables 1+2 are better movies than Se7en, Fightclub, Memento or V for Vendetta. But the Expendables is a movie that you just pop in, drink a beer and have a good time with your friends. While being bad in many aspects, it is entertaining.

Yeah, buggy broken games are definitely worse than bug free ones. Look at ET and Superman 64 compared to Ocarina of Time or Super Mario 64. Two of them went into the trash heap, two of them were instant classics. So you could say that on a quality level, a game can be better than another. Although Skyrim was one of my favorite games of all time and it was really buggy. You could also look at quality of design and determine that one game was better than another... In the end though I think you could analyze all those points and always come up with a conflicting argument. So if you define the purpose of games to be entertaining people then the "better game" would be totally subjective. Just like one painting can't be truly "better" than another.