I'm contemplating Silver.
1. Apple doesn't ship a black charger yet it does with a black cable. Not really a dealbreaker tbh but just something I noticed it would be far down the list imo
2. Ports will show more wear with Space Black, that's my main concern.
3. Fingerprints is still noticeable even on the demo Apple Store units which they clean a lot...
Even though apple claims its fingerprint resistant it will still be more obvious due to the dark nature. I mean look at the keyboards already, That's why when I'm at home I use an external keyboard and mouse wireless to prolong the life of the keyboard.
4. Silver is just a timeless apple design look, like you know it's Apple.
5. #2, less likely to show wear and tear as it's original colour.
Basically personal preference, it's up to you. My reasons were just as above, I don't know if they'll apply to you but if they do then I'm glad it was some information.