Donkeys are excellent indicators of stuff around. Watch the ears.
The best call so far is a johnny Stewart dog howler or a name real similar.
I don't think the brand matters as much as the design, with the open reed type you can play different 'notes' , for lack of a better term.
The last month or so I have been just making yipping noises I think the rabbit distress sounds may have been played out in my area.
I think that you will find differing sounds that work in your area.
I am in a heavy mesquite area, so I have to get all my critters fairly close up, so there probably many coyotes that I called in that I never saw.