You can do both. First take out the loan, and then put them on the market as lease only.
You may well have the same problems with leasing them out though, that there are a lot of them available, and most airlines have moved on from using them. But as you say, owning them and just having them sit on the market still helps your CV, and gives you more access to loans. If you're planning to open a new base, then your best option may be to actually fly them yourself, and generate more profit.