Would a Surface or a MacBook be better for philosophy and economics?
I would also most likely be downloading and playing smaller games, but no heavy gaming.
…or would another computer work better?
I have no knowledge about a Surface, but I currently have a 13" MacBook Pro w/ Retina Display. I recommend Macs to anyone I know. I burned through 2 Dells and the stability of my Mac is amazing. However I do not recommend the MacBook Air, my friends have had issues with them. I use my computer a lot for personal use, watching YouTube/Netflix, social media, video editing, Photoshop, and school work (note-taking, papers, and a few online classes). It’s awesome honestly. It’s be reliable. It is my 2nd Macbook pro, I had one from 7th grade - 9th and received a new one for my birthday as a freshman. I will probably get another when I go to college, however I use mine at least over 4 hours a day so that’s why I purchase new ones more often than others. 
Either of those computers would work. You’re not in a major that requires a really high powered computer, and you’re not looking to do a ton of gaming. That means pretty much anything on market $400+ should get the job done. The mac and surface will definitely do what you need them to attend look nice doing so, but they’re much pricier than a lot of other options.
I don’t think macs are necessarily more reliable than a lot of the competition, either. Two of my roommates are currently having serious issues with theirs due to pregnant batteries. I had a netbook that lasted me 5 years on very heavy usage and abuse. Dell makes low-priced computers. They get the job done, but they probably won’t be the most durable. Basically, if you want something that will last a long time, job for built quality, which will mean a slightly higher price tag. If you plan to upgrade in 2-3 years, go ahead and get a cheaper computer.