The worst candidate for a lease: someone who can’t afford to pay an early termination penalty. For this reason, leasing is not a prudent choice for someone who’s financially strapped. (They should buy a good used car.)
The second worst candidate: someone who wants to end up owning the vehicle. Buying a car at the end defeats the purpose of leasing, which is to drive a new car every 2-3 years with no trade-in hassles. And if a lease deal was a good one to begin with (i.e., low monthly payments with a high residual), the car usually won’t be worth buying at the residual/purchase option price. Other poor candidates: people who drive a lot of miles (over 15,000 miles per year), and those who fail to take good care of their cars.