Self Lender (now known as Self) is not necessarily better than a second-chance credit card. Self offers credit-builder loans that help people with low scores improve their credit standing. Borrowers pay money into a CD every month, and then get access to that money at the end, but they're charged fees and interest.
With a second-chance credit card, you may have the opportunity to get a card with a $0 annual fee and can avoid interest if you always pay in full. Plus, a credit card helps you build credit indefinitely, while a credit-builder loan from Self is temporary.