It's difficult to compare them side-by-side because the two systems are so different, and are suited for different types of games. Which one is "better" for you really depends on what type of games you like. As someone who owns 93 original Intellivision cartridges and over 150 original 2600 cartridges, I would say that the Intellivision library, both first-party and third-party, has a higher percentage
of high-quality games than the 2600 library does, even though it is smaller at 125 released titles. The Intellivision isn't a system I grew up with, either: I've been playing the 2600 since about 1981, but I hadn't even seen an Intellivision until I was in my early thirties.
I compared the two systems in more detail in the Intellivision forum:
jaybird3rd, on Mon Sep 6, 2010 2:24 PM, said:
If you ask people who grew up on Atari consoles what they don't like about the Intellivision, the answers you'll get basically boil down to "I don't like it because it isn't an Atari": the controllers are different, the graphics look different, the types of games in its library are different, etc. I think what helped me is that nostalgia doesn't play much of a role for me when I sit down to play a game on a classic computer or console: I still like playing the games I played when I was a kid, but I'm not so limited by my experience that I can't appreciate something different on its own terms.
Regarding the much-maligned hand controllers: in my opinion, the main stumbling block that modern gamers have to overcome is their familiarity with gamepads. If you try to use the hand controller like a gamepad, as newcomers to the system often do, you're only making it harder on yourself because that isn't the best way to use it. For side-to-side games like Astrosmash, use your index and middle fingers to "rock" the disc back and forth; for four-direction games (like Snafu), I often find that it's easier to "spin" the disc around in a circle with your index finger to reach the directionals, rather than manhandling it by pushing it up, down, left, or right with your thumb. You have to find a method that works for you, but again, don't approach it like a gamepad! It also helps if you can find a way of holding the controllers that makes the side buttons more comfortable.
Once you get used to them, you'll find that the hand controllers aren't as bad as their reputation might suggest: they offer sixteen directions, a feature unique to the Intellivision and Aquarius (and yes, it does make a difference in games that were designed for it). They also offer a keypad for secondary input, an idea that the Atari 2600 needed a whole separate controller to implement.
jaybird3rd, on Mon Sep 6, 2010 9:56 PM, said:
As far as the Intellivision software is concerned, it's inevitable that Intellivision games and Atari games are very different, because both consoles are different and were designed to appeal to different audiences.
The 2600 was intended primarily for home conversions of popular arcade games, and the initial games that were made for it reflected that. On the other hand, the Intellivision seems to have been aimed at more of an upscale market: it was much more expensive, it was advertised in mature outlets like Playboy Magazine, its woodgrain and brown plastic case didn't look like something that belonged on a spaceship, its pitchman was the urbane and erudite George Plimpton, and its games were seen as more sophisticated and more realistic ("the closest thing to the real thing"). Its initial library of games were aimed at a wider audience than kids who hung out at video arcades, so you had very detailed implementations of classic games (card games, board games, Horse Racing, etc), sports games, simulations, and other types of games that the general public was familiar with. So, in the beginning, the Atari was the "kid's console," while the Intellivision was the "thinking man's console" (hence its full name, "Intelligent Television").
As the video game market grew more competitive, and as it became clear that space shooters and arcade games were driving more sales, the game ideas for both consoles became more intermingled: the Intellivision gradually got more arcade-style games, while the 2600 got more detailed and sophisticated games. But in both cases, the game designs were closely tied to the capabilities of the hardware, and games that were designed for one couldn't easily be ported to the other. So, out of necessity, the two consoles maintained very different personalities, and Intellivision games certainly have a different "feel" than Atari games as a result. You'll either like them or you won't, but it's a mistake to dismiss them merely because they aren't just like what you might have played when you were a kid. I think the 2600 turned out to be the more versatile of the two platforms because its minimalist design was more flexible (again, a happy accident on Atari's part), but the Intellivision still has a lot to offer, and if you're willing to expand your horizons a bit and give it an honest chance, you may find that you'll like it.