I've actually lived at both, and you're right they're pretty different. I'd echo the previous comments that you really want to live near Downtown SS where the Metro is (which is why some places in SS are way more expensive than others). SS is huge geographically and can get a little dodgy as you go toward PG County.

SS Pros:

• Livelier: Two movie theaters, a concert hall, a skating rink in the winter, events downtown, huge new library, etc.
• Cheaper: DTSS isn't cheap by any means, but you'll still save a good deal over CC or anywhere in NoVA to be honest.
• No more bridges if you have to drive into DC (not that 16th St. is exactly a joy to drive, but still.)
• Way more diverse: As a POC you certainly wouldn't feel less comfortable for sure
• Restaurants: Do you like Ethiopian food? If so, SS has plenty of options for you.
• Much younger: SS is geared a lot more towards college kids/hipsters/millenials rather than the typical relatively affluent high-20s/30s young professional

Cons:

• Less upscale: Some would see this as a pro to be honest. NoVA in general is a lot more upscale than anywhere in MD that isn't Bethesda, and CC is definitely part of that.
• The Red Line: It's as bad as you've heard. Not to mention they're shutting down a section in a few months that'll cut SS off from DC
• The Red Line 2: SS is definitely on the dodgier side of the Red Line. Hardly an issue for rush hour or with friends or whatever, but if you're used to taking the train home alone late at night be aware.
• Restaurants: Probably biased because I'm not a fan of Ethiopian food and a little salty that the recently closed Jackie's is being replaced by yet another Ethiopian restaurant, but I don't see how people are saying SS has better dining options. CC is actually really great in this regard, whereas SS does have "variety", but some of those options are kinda not great
• Safety: I'll say this right now, SS is in no way unsafe. It's very safe, just probably not as safe as CC. Walking home late at night by yourself down Fenton St or even Georgia Ave, it's a good idea to keep the headphones out and be aware of your surroundings (which is good advice anywhere).
• Taxes: You're going to pay more in taxes in MD. Especially if you don't own a car.