I've never felt the need for any additional "sway control" on my setup. I have decent TW % and the axles on my trailer are located on the rear 1/3 of the trailer, so with them being 2/3 of the way back from the hitch, I've never experienced "sway".. Even with high winds, being passed by semi's, a couple of emergency maneuvers, going down hill....
Folks swear by those add on friction sway devices that you add to your setup. Others swear by the WD hitches with "built-in" sway control, like the Equal-I-Zer's or Dual Cams or others and they are all fine depending on what your rig needs.
My EAZ-Lift only cost $250 back in 2002. Not sure what they cost now, but it's been a perfect setup for me.
I've been towing trailers for over 30 years, so I've found out that just loading them correctly makes most of the difference.. At least for those kinds of trailers that you can adjust the load..
TT's, you don't have that many options on how it's loaded because it all depends on how far back the axles are and where the storage is, or where the fresh water tank is and on and on..
Without really knowing more about the trailer you have in mind, it's hard to say one way or the other what you might need or not..
Mitch