A set-top box is often the single largest hardware line in an operator's budget, and it grows with every subscriber you add. So how the box reaches the home isn't a logistics detail: it sets your cash flow, what sits on your balance sheet, and how hard it is for a subscriber to leave. The box itself is identical in all three models. The decision is purely financial.
And it's rarely one decision. The same operator can subsidize boxes to win premium and triple-play subscribers, lease to the mainstream base, and sell outright to prepaid, B2B or second-TV customers — then move subscribers between models over time. The real question isn't “which model,” it's “which model for which subscriber, and how do I keep it safe?”