Cap One is considered by to sub-prime. However, it's a good card to rebuild or start with. Cards just don't grow with you and they're not good about giving too many credit line increases.
2009 Cap One approved a card for 300 dollar credit. I activated it over the phone, went to the store to use the card and was told the card was invalid!
I NEVER used the card yet it is now on my credit report for THREE HUNDRED DOLLARS!
What to do?
Capital One has many different cards and are not just subprime.
I have a personal card opened at $10k limit, which is now $18K. I also have a CapOne business card opened at $15K, now raised to $20K. Reasonable rewards, no fees, and no complaints other than they pulled all three CRAs for approval.