Not sure what research you're doing, but monotube shocks are generally very firm, and will likely give a "stiff" ride.
Twin-tube low pressure shocks generally give a smoother ride, but lack the control of monotubes, particularly at high speed on unpaved roads.
By far the "best" shocks, in terms of performance, would probably be Bilsteins. You can get 5100 series shocks for the front made for a 4 inch lift, and use factory length HD series shocks for the rear with modified lower shock mounts for clearance.
However, Bilsteins are VERY firm and depending on tire choice and the spring setup, can ride like a sports car.
If you want a softer ride, you may want to get some less expensive twin-tube shocks, something like Monroe/Gabriel cheapos, or KYB GR-2/Excel-G for a quality set. You will have to get an F-150/Bronco shock for the front to get a longer shock, the stock Explorer shock will not be long enough for the lift.
There are plenty of other choices out there, Monroe makes the Rancho shocks in a few varieties for the Explorer, and there are the Eldebrocks and a few others. I'd say the Bilsteins are the best, both in terms of performance and value, since they have a lifetime replacement warranty, but again, depending on the setup, they can ride VERY firm, with harsh springs and heavy tires and hard bushings, they can rattle your teeth on rough roads.
