I have 2 half-sheets and 2 quarter-sheets. (The sheet pan is what professional bakeries use. They come in full, half, and quarter. They have a lip all the way around and sometimes are referred to as jellyroll pans. You can get them at any kitchen shop but I would recommend getting a couple from a restaurant supply store as they will be MUCH cheaper.
The rimmed sheet pan is one of those things in a kitchen that has multiple uses. I often use mine both for baking and for roasting. If you have something going in your oven with the potential to spill over throwing one under what you’re putting in the oven can catch all the drips and over flow.
When doing my slow-roasted tomato sauce these are perfect as they keep everything on the pan and contains all the juices the tomatoes and other produce may put off. I also use these pans for making my Garlic Brussels Chips by lining them with foil and then pouring the prepares Brussel Sprouts on them and roasting them in the oven. Since they are coasted in butter and oil the rim ensures I don’t make a mess of my oven.
Using standard sized rimmed sheet pans you can also easily find Silpats to fit them. These are essential for any baker. No more burning or things sticking to the pan. You don’t even need to grease the pan anymore. Cookies come right off and things as delicate as croissants don’t have to be manhandled to remove. This is also the pan you need for any type of jelly roll or cakes the the Yule Log.
A decent sheet pan usually runs anywhere from $10-$15 a pan and it worth every bit of it. Places like Williams Sonoma will have slightly more expensive ones with special non-stick coating but with use of the silpats I don’t find it’s necessarily worth paying for the “non-stick”. I have found however the Williams Sonoma ones tend to be a bit more solid and they do have some better engineering in the air flow design. The ones I purchased from the restaurant supply store work perfectly well. It just meant the first time cooking anything on them I needed to pay attention to time and tweak a little as they conducted heat a little differently.