The first question to ask yourself is are you going to use this tub as a shower as well? A drop-in is designed to literally drop into a deck. While it can be tweaked to be used for a shower, it's and add-on kit and can fail and leak.
A skirted tub is (often) a traditional tub designed for an alcove, and has provisions (usually) for use as a shower - it has a flange around the edges to retain water from the spray.
A jetted tub may be best installed with an in-line heater, adding to the cost in both installation and energy use. Also, a jetted tub requires regular cleaning, both inside and internal to keep the water passages from growing nasty stuff - the chemicals are a necessary evil. You don't want it spewing mold and scum out of the internal passages when you get around to use it. You are limited to what you can put into the tub with a jetted design.
Personally, I went with an air tub. Not as vigorous, but easier to keep clean. You don't have to worry about the kids turning the pump on when the tub isn't full and ruining it and (most) turn the air turbine on after a delay to blow dry the internal passages, so no problems with accidentially turning it on. You can use any oils, scents, bubbles you want with an air tub as well.