The advantage of the drop-in charger type is that it provides a place for the radio to sit in an upright position instead of just laying down on a surface. The drop-in charger provides a less cluttered appearance. Some drop-in chargers also have a slot to charge a spare battery so you can quickly swap out a battery should your radio run low on power.
There are also drop-in chargers that let you charge multiple units at one time. This is good when you have staff that all carry radios that need to be charged at the same time. If you had a separate charger for each unit, you'll need a lot of power outlets to plug all of them in. If you have a six unit multi-charger for instance, you only need one outlet to charge all your radios. This also gives a less cluttered appearance. The multi-unit charger may not have a slot for a spare battery so this is something to consider if your frequently use your two-way radios so much you run the power down.