I feel funny about that, and it can't be as fresh, can it?
I grew my own garlic this year, so I'll be peeling garlic forever. But if it's any help, I've taken to keeping a jar of minced ginger in my fridge. When I only need a Tbsp at a time, it's so much easier!
Cook's Illustrated recommends buying the pre-peeled and freezing it. It preserves the flavor and saves a whole lot of time. I use a microplane grater, and grate it into my dish right from frozen - it defrosts almost instantly.
I like fresh garlic. One of the best tricks I learned on this site is how to just smash the clove with a meat pounder - the peel comes right off.
I use the side of my chef's knife to knock the garlic. (Sometimes you want to keep it whole) the skin slips off easily after that. I can't imagine why I would buy already peeled garlic. I want mine to be as fresh as possible.
Most professional kitchens will buy the garlic pre-peeled (but still whole cloves) because it takes time to peel it - thus labor cost, for an indiscernible gain of fresher unpeeled garlic. Peeling through 5 pounds of garlic a week would add significant cost to a business with already thin margins! A sachet is usually included to keep the garlic from getting too moist and going bad.
Do what's more convenient/preferable for you - but don't use the jarred minced stuff, with that there IS a huge difference.
If you're using a lot of garlic every week, then go ahead and get the pre-peeled stuff. It's great. It's definitely fresh. The old stuff looks wrinkly if not discolored (sort of reddish and white). Every few months I get a bag of it (~1lb) from my Korean supermarket to make garlic oil and confit. It keeps in the fridge for about a week or so. Tends to keep longer if it is kept dry and refrigerated.
I'd never get pre-peeled just because I've never minded using whole garlic! Just whack it with a knife presto, the peel separates. Seems like there isn't a huge difference according to previous posters so go with whatever you think would be easier for yourself.
Another note; the pre-peeled stuff that you purchase in a jar has a remarkably short shelf life whereas whole unpeeled cloves can hang around for awhile. The idea of frozen garlic is, well, bleh! Restaurants do go through tons of garlic (and salt, and butter) but make your decision on how frequently you use it. It's one thing to peel two or three cloves (easy) but if you are using up maybe 100 than that's different.
Yes, the two, three and four star restaurants may use bulk pre peeled, but in five star and Michelin starred restaurants they assign the peeling and chopping to the apprentice each morning.
Pierino and Sarah Reinertsen are spot-on. Commercial kitchens can't afford to basically have a person in the kitchen whose job is to do nothing but smash, peel, and mince garlic. At the same time, peeled garlic has a short shelf-life; it turns slimy and molds within about 7 to 10 days. Fortunately, most commercial kitchens go through it easily more rapidly than that (and they turn it into roasted garlic if it ends up on the cusp). So your chef's recommendation is great if you operate a restaurant; if not, smash, peel and mince your own. Here is an interesting conversation about peeling garlic:
A friend who owns a restaurant that uses a lot of garlic points out that much of the bulk pre-peeled garlic comes from China. I've read that competition from inexpensive Chinese garlic has put a lot of pressure on California growers.
I totally agree with using a meat pounder to peel garlic. Give the clove a few good whaps and the peel should come right off. I know technically sometimes recipes don't want the garlic bruised - but whatever. If you don't want too much garlic flavor, just hold back a little of what you throw in the dish. Not only is this way easy, but it's fun too!!!