Rent to own is never a good idea, especially for the buyer. Either you're going to rent, or you're going to buy. Rent to own was more common when we were in a buyer's market and sellers were desperate for buyers. We are now in a very healthy seller's market in most areas. Sellers are able to SELL their homes to qualified buyers very easily.
I assume you can't buy due to credit issues? I suggest you talk to a lender and see what's keeping you from getting a mortgage. Then fix whatever you need to fix -- credit score, savings, reduce your debts, etc.