We use Heart Guard Plus because it is what our vet has recommended. I haven't researched alternatives and I'm also interested in seeing what the consensus is here. We have a year’s supply of Heart Guard Plus on hand for each of our dogs and cat so I don't imagine we will be making any changes any time soon.
I do know someone who buys ivermectin in bulk (for cattle use) and uses it for her dozen or so hounds. It doesn't have the advantage of the Plus ingredient (sorry, I'm being lazy and not looking the name of it up) so I decided I wasn't going that route. We also don't have the expense of maintaining a pack the size of what she does.
I prefer Interceptor and it is what I use. The reason? Well, because I wont use Heartguard/Frontline products again, and their customer service is RUDE RUDE RUDE. (I had an incident with my couch and frontline and while I take partial responsibility, it was the way they treated me when I called them about it)
I'm so sorry this didn't have a better outcome. They really should have worked with you and there is absolutely no excuse for rude behavior. Sounds like their staff needs some training in phone etiquette and their management could benefit in learning about building customer relationships.
My personal and work experience with pharma has been very different. I'm appalled at the way Merial treated you and their lack of responsiveness. I remember the couch incident well and what I was hoping for was for you to be treated the way my wife was by Proctor & Gamble after she spilled some Comet on our vinyl bathroom floor. She had accidently knocked over a container and didn't think anything of it so she didn't clean it up right away. The Comet ate into the vinyl and left blue stains. She called P&G to let them know there was no warning on the container. She really didn't expect anything more then an opportunity to vent. The customer service rep apologized and requested we send them a picture of the floor and an estimate for having it replaced. She was shocked and yes, P&G did pay to have the floor redone without us having to ask them to do it.
I guess I should have sent you a PM to find out what happened after you called them. I was hoping no news was good news.
Sorry for getting off topic.