I use Tritronics collars. I got them because the stock manager here had four border collies and he did a bunch of research into the collars and ended up with a four dog Tritronic setup.
I got a one dog model then I got two dogs. So, I had to sell my one dogger and purchase a two dog model. Nope, as tempting as it is, I won't have more than two -- I value my sanity.

Good news was the one dogger sold quick, the bad news is I didn't have enough foresight to get the two dog first. Oh well, you know what they say about a fool and his money.

Moral of the story is plan ahead.
When ever we go out for a walk, bike, ski, or head into the woods for the week the collars go on. That way they love them -- "Oh joy, its time to herd something, and I don't care what... bike. . okay, skis... . okay, ground squirrels or tree squirrels... . okay, horse or mule... . okay, well sometimes, deer or elk..... ah... . nope!" They vie for position, who gets to be the first to get a collar on.
Starr is so sharp that, even though I hide the control inside my coat, when I put my hand ... . just so... . she knows whats coming (not good because they aren't suppose to know). "See I'm behaving, I didn't mean it, really!" She too smart for her own good. Fortunately, I have to use it very rarely.