"assuming nothing goes wrong before then" - The problem is something ALWAYS goes wrong and you lose all the money you put in.
If you don't have credit problems, get a mortgage and buy a home.
In rent to own you lose the house and all your money if...LL doesn't pay his mortgage, LL doesn't pay his property taxes, LL files bankruptcy, LL decides to sell, you can't secure financing when the time comes, LL dies, etc. A thousand ways to lose your money in rent to own, it's so bad some states are considering making it illegal. That should tell you all you need to know.