needed a little help deciding on what martial art to choose
You might read
this thread. It takes a couple pages to get going, but it has a lot of useful information.
I recommend you tour the studios in your area. Explain honestly that you want to study but haven't decided on a style yet. Ask to watch an advanced class and ask for a free trial lesson. Schools will almost always say yes to this. Don't immediately sign up at the first school you visit, no matter how awesome it seems. Check out several schools. Be sure to show up to watch an
advacned class, not a beginner class. They will probably recommend you watch a beginner class because it what you'd be doing if you signed up. That doesn't matter. You want to see what people look like after they've been studying for years.
Something that I know will let me hold my own in a fight
This is complicated. There are reasons why
mixed martial arts is a thing. If your goal is solely to be able to hold your own in a fight, I think I would recommend a cardio/kickboxing class. Something where you learn almost no techniques beyond how to not hurt yourself, and simply spend an hour at a time jumping up and down and punching and kicking a bag. The exercise will make your body stronger and tougher, and lots and lots of time punching and kicking a bag will tend to make you competent at punching and kicking stuff. It's very different hitting a person vs hitting the air, and even if you spend years punching the air, the first time you actually make contact with something you're as likely to hurt yourself as your opponent.
Then there's the groundwork issue. An awful lot of real fights end up on the ground. A lot of traditional upright training is difficult to apply from the ground. But you have to be on the ground before most groundwork training is applicable, and a lot of it lacks real life applicability. For example, if you're in the stereotypical high school face off when the one one kid is pushing you in the chest while his buddies flank you, it's probably going to be a whole lot more useful to knock the guy pushing you out then look at his buddies in the eye then it is to take the guy pushing you to the ground while his buddies kick you in the head.
Then there's issue of silly assumptions. Karate schools will generally have you go barefoot and wear clothes that you'd never wear in daily life. Kicking with shoes on or off is different. Learning grappling techniques that depend on grabbing parts of clothing that nobody wears outside of a dojo is silly. And an awful lot of karate fundamentally assumes that you will always be standing upright. Karate derives a great deal of its power from the way it interacts with the ground. If somebody takes a karateka off their feet, suddenly they've lost a great deal of their ability to do damage. Even your average high school wrestler with no "fight" training at all stands a pretty good chance against a traditionally trained karateka with similar training time. But you can't say "wrestling beats karate" because wrestling makes just as many silly assumptions. You don't want to be the guy who took western sport style of wrestling, take an opponent to the ground and feel good about how you've won...only to have the guy punch you in the face because the holds you're using don't prevent that because it's "against the rules" in wrestling to punch someone in the face.
for self defense
If self defense is your sole goal, not aesthetics, not sport, not having fun, not "coolness factor" or anything else, and you simulatenously don't want to make a career or lifestyle out of cross training multiple styles, then I suggest you tour the available schools and try to find something simple, that focuses on aerobics, strength training and bag work. No bowing, no kata, no boxing gloves, no fighting in a ring for points on a small and specific list of 'approved' target areas, no esoteric philosophy and tradition, just raw physical training and hitting stuff.
and general fun with friends
Ahh. Again: tour the schools in your area. Find out what's available. Some schools is are simply bad. Choosing a style on name only because you like the style might not get you the same results as choosing a
school because you like the school. Even a style that's not very good for fighting will help your body to become more durable. And it might be more fun for you and your friends than hours of bag work every week.