Controllers for what, specifically?
Answers probably be very different for:
-- little RC motor controllers
vs
-- generic low-power (few hundred watt) ebike controllers
vs
-- OEM ebike controllers
vs
-- ebike controllers that have to fit in a specific size/space/shape
vs
-- the same things in high power (thousands of watt) levels
vs
-- large-EV controllers for several to dozens of kW,
etc.
Also, you should state what exactly you need done, and your budget, because it is different for a small repair, vs a complete custom built controller from the ground up, etc.