I was browsing in the kitchenware department of one of the department stores in town today, looking at the huge Zyliss display. Zyliss , as you probably know if you are into your kitchen gadgets, is a Swiss company that makes a lot of useful things. I have a number of Zyliss products in my kitchen, but my favorite one at the moment is the Soft Skin Peeler , aka the Tomato Peeler. This wonderful thing can take the skin off of any soft fruit like tomatoes and peaches with amazing ease. It even shaves truffles very thin!
The one I have is the Y shaped one, which doesn't seem to be available in the U.S.  yet. The I-shaped one is, but I'm firmly in the Y camp when it comes to peelers, mainly because I'm left handed and the I shape goes the 'wrong way' for me. I think that the Y shape is a lot more practical. In Japan, the I shape is practically unknown, but almost every household has at least one Y shaped peeler I think.
But I know a lot of people who swear by the I shape. Years ago at our wedding reception, the best man devised several games, one of which was a very Swiss potato peeling contest amongst the women! (Yes, some thoughts about the political un-correctness of that did come to mind but I was too overwrought by the whole Wedding Thing to bring it up.) The game was fun anyway, but I had no chance since the only peelers provided were the I shaped ones. The winner, a veteran I-shape user, managed to peel a potato in under 15 seconds.
I feel a tiny bit guilty when I use a peeler because I'm not using a knife. That comes from growing up in Japan, where everyone until recently was supposed to be able to do execute the most intricate cutting techniques with just a couple of knives. Never mind though, I love my Y shaped peelers.