There are 3 benefits to leasing:
1. You only pay about half the sales tax (this will save you around $2K-$3K per car)
2. Automakers set the lease price based on predicted depreciation, so if they're wrong and the car proves to be a turkey (e.g. BMW i3, 1st gen Leaf, etc.) at least you won't own that extra depreciation.
3. Writing off the lease for your business might have some tax advantages that are preferable to a purchase write off in some cases.
The caveats are:
1. They know you're saving some tax so they just charge more.
2. They know that you've been lured by the lower monthly payment so they just charge more.
3. A lease is by far the most solid and permanent commitment you can make to a car. You are freakin' stuck with it.
4. When returning the lease they will charge you fees for everything in the (literal) book. If your tires have been used, they'll say they need replacement. Same for the brakes. And everything needs to be OEM (replaced windshield, tire brand, etc.) or they fine you. By comparison, when returning a purchased car they just glance out thru their office window and check the "Excellent" box on Kelley Blue Book.
So the bottom line is that if you can spot the next big turkey (Hummer, Fiat, etc.) and lease it just at the moment the automaker's desperation is peaking, you might save $100 or so by committing to the profound hassle of a lease.
And the top line is that if you choose the lease because that's all you can afford, you'll only make yourself poorer in the process.