Just my opinion:
Electronic calls are really cool. Some use digital recordings of real animals or people using calls really well. They range in quality from awful to life-like.
You can get an OK varmint caller for $100. It will work OK. You and your friends will be impressed. You will kill some coyotes.
You can get a much, much better caller for $150. It will work much, much better. You and your friends will be delighted. You will kill some coyotes.
You can get an outstanding caller for $200. It will amaze you and your friends. You will kill some coyotes.
You can spend $2,000 on a caller with remote control, action lure, multiple sounds, etc. At a certain point, varmint callers are designed to lure in hunters.
All that means nothing to a coyote. They want it to sound like dinner. Or another coyote. Or whatever it is you are trying to make sound interesting to them.
Years ago, I used a mouth call. I thought I was pretty good. My friends thought I was pretty good. I killed some coyotes. Then one day, someone told me that most coyotes would come in, circle, and I was never seeing most of the coyotes that came in. I didn't really believe it until I set up about a mile away and watched another experienced caller work through a spotting scope. It's nearly impossible to see them all. They circle downwind, they listen for the sounds of injured prey or other predators, look for movement, look for ravens or crows moving in, etc. Sometimes they rush in, sometimes they sit and watch. In short, they act like they are going to act, we try to fool them into coming out to play.