I never leased and I don't think I could do it. I like to do things my way - my tack, my feed regime, my training time-line and working routine, health care done my way, etc.
Not only that, I am more comfortable if its mine. I hate borrowing things - fearful something is going to happen. I'd feel the same way towards a lease even if everything is outlined in a contract.
Not to mention I tend to get attached to them and would hate to have to give up a lease horse if I'm not ready.