What do you plan to store in your pantry? Everyday food items? Bulk buys? Paper products? Cooking/prep utensils and cookware? Appliances? Cleaning tools?

Free-standing shelving as you describe will give you less flexibility, not more. Your shelf heights will be fixed - and there will not be enough of them. 12" shelves suggests storage of smaller items (canned goods, box mixes, small appliances). For those kinds of items, you want the shelves to be only slightly higher than the items on the shelf, so things don't have to be stacked.

I use an old chest of drawers as storage in my laundry room/workshop. Something like that could be useful for some kinds of pantry storage.

Sorry I've been away.........

My intention is to store mostly bulky paper products, rarely used appliances (like my bread maker), cleaning supplies and tools, and a smaller amount of long-term food products like canned goods and baking supplies. I don't know why you think my shelf height will be fixed, since it can be changed with a mallet and a little dexterity ;) though my plan is to not do that very often.

My first thought is, Go with Elfa shelving. You attach straight pieces to the wall, and you can move items around in the future -- you can have drawers or shelves, as you wish. Do you have a Container Store in your area? You can see it all in person.

I use Metro units for a lot of storage. For appliances, I don't like it so well unless the appliances are stored in their boxes (and some are, to ward off the dust). The feet of the appliances slip between the wires, and if they go through in one spot but sit atop the wire on the other side, well, they are cattywhompus. Same for small items. So you need trays, dishdrainer bases, etc, under some things. I do like that you can hang baskets and hooks on the metro for more storage.

i do like the Container Store's elfa. I use that as much as the Metro! And you can get freestanding elfa if you really don't want to drill holds along the top of the wall. But there is so much flexibility with elfa, including adding drawers, varying depths of shelves, option for a counter in the middle, flat hanging against the back wall, etc. and you can mix wire and solid shelving.

Container Store has a good sale 25% off the shelving in late July-August, and 30% off all elfa in December-early February.

I know what you mean about things not standing fully level\
on the wired shelves, but I'm working with it, and I like what I ended up doing: 2 towers of wired shelves - one 12" deep and one 18" deep. As you can see, I'm only starting to fill them, and am using them for cookware and hardware as well as food and storage containers, etc.