I'm wondering what would look better to colleges:

A game that's quite successful, and is written in Unity, or a game written with something like Monogame, requiring more focus on lower level stuff? I'd like to build up a decent portfolio by the time college rolls around in 3 years. I'd rather not have a bunch of Unity games that sold well, if they're not really interested in that sort of stuff.

Which would colleges like more?

Are we talking about applying for college (just plain education? scholarship? as a professor?), or something else?

When I applied to colleges, they only cared about what my education record was and whether I could pay tuition. I didn't tell them about any of my hobby projects.

A lot of the people I met in college had never programmed before that moment.

Applying as a student, preferably with a scholarship.

Moving to the career section of the site.

For a college choice, most won't care. As Nypyren wrote, that isn't what they care about, and that isn't what post-secondary studies are for. You go there not for job training but to be exposed to a lot of ideas that you normally would not be exposed to, and to work with things you otherwise might not. You will have to take courses on a wide range of subjects not because you want to enjoy the subject, but because you need some exposure to topics you normally would rather avoid. Study of databases. Study of algorithmic complexity. Study of other unpopular topics. Many CS programs require study of technical writing and some communications classes, in addition to a school's general education requirements.

When you have finished your academic career and enter the workforce, your employer will be VERY interested to see your projects. They want evidence that you can do the job well, that you are interested in games specifically. If you can show you have completed several small hobby games, that is great evidence that you will fit with the company and will be able to do the job.

So making a good game with Unity is better than making an OK game with Monogame?

I think any of that stuff you mentioned would make a good addition to your application. Nobody really expects applicants to have made games that have earned a profit already.

Neither is better than the other.
Some people will be impressed if you know the low level stuff and make your own engine whilst others would be impressed that you can use an existing tool and make a commercial game without reinventing the wheel.

Just do what you find more interesting.

Ok, that's cool! Thanks for the help.

Personally I expect a recent graduate to have no real-world programming experience. Some hold a programming-related job while in school, but that is about the best you can expect.

I look for passion about making games. Something that tells me they care about game mechanics. If they describe how they run their own D&D group and build up the worlds, if they describe that they participated in GameJam or similar events, if they describe how they built their own side games, that shows the right kind of interest. If they tell you about their favorite level of a blockbuster game, or tell you they enjoy playing RPGs and hope that is what you are making, that is the wrong kind of interest.

Note that it won't really help you much on the career ladder, you'll still be hired as an entry level position.

It will help you get to and through the interview favorably. That's good if you're looking for a job.

Ok, thanks! I'd really like it if I could do some freelancing after getting some experience. Some side money would be nice, since I don't want to work at the supermarket