Following this thread: Looking to do the same so I can utilize plugins with my Studiologic SL88 controller. Trying to be as simple & lightweight as possible (possible to do this on an iPad)?
iPads don't run plugins per se, but there are plenty of apps you can trigger from your SL88. For some things, like pianos/EPs and orchestral instruments, the iPad apps are generally not as good as the best Windows/Mac VSTs (though they can still be quite good, and it's always subjective to some extent); for other things, the iPad is arguably just as good, like for some of the VA synth stuff, or the well regarded B3X Hammond organ app which is supposedly identical on Mac, Windows, and iPad (but much cheaper on iPad), and they tend to have nice interfaces.
Summing it up, I'd say:
Windows: maximum selection and flexibility, available touchscreen (works better for some apps than others), biggest nuisance to setup and configure and keep stable (between the auto-updating and the way adding something new can alter how things were working and it can then be hard to "undo" the change you made... you know, typical Windows stuff ;-) )
Mac: selection/flexibility almost as good as Windows, much easier to setup and configure and keep stable (no forced updates, better MIDI/audio support at the OS level), no tablet/touchscreen option, pricier base unit than Windows but can be cheaper in total since you may be able to get by with the $30 Mainstage software and no external audio interface
iPad: easiest to setup and configure, most portable, everything touchscreen optimized, well-priced apps. The limited configuration options is a double-edged sword... if your setup is working the way you want it will probably stay that way, but if something isn't working right for you right off the bat, there will probably be no way to fix it. ;-) Nicely, you can defer unwanted updates indefinitely; but on the downside, once you upgrade, there's no way to go back (unlike on a Mac).