I use a powdered form. Having garlic jar is useless as we don't utilize garlic in the way it's premade. When my mom buys garlic, she ONLY buys enough for the upcoming dinner for the next two or so nights, so I can't take one...otherwise it'll taste funny. And it won't even last too long.
I use McCormick's Garlic powder. It works fine, the only ingredient is garlic, no additives. Just add the powder into water and go. Just in case the other two choices didn't work out for anyone (it doesn't for me...)