If it were mine I'd want a combination of things not just a shelving unit that will only hold certain sized items or boxes. I'd want pegboard for things I could hang--like extention cords. I'd want some wide and widely spaced shelves for bulky items and some narrow closely spaced shelves for small items. And I would like some space left free for things that wouldn't fit on shelves.

Of course it all depends on what you would be storing there. I would suggest you take stock of what would go in there and work from there. Perhaps just do one wall for now and add more storage as the need arises.

Whatever you do, if you have kids make sure it is secured to the wall. Kids have a tendancy to climb shelves to reach the top--heck even adults do that-- and a front loaded shelving unit may fall and it would be right on top of them.

We lined our storage room with shelf standards mounted on the walls into the studs. The standards are permanently mounted, but the shelf brackets and shelves can be rearranged as our storage needs change. It's worked well.

The best thing to do is determine what will be store in the room by putting everything into that room. Then go through it all and decide if you will really use it or if it's just taking up space. Now sort like items together. Holiday decorations, seasonal items, etc. While you are doing this sort, again decide if you are really going to use the items.

It will be easier to decide what type of storage you need once you have a clear idea of what needs to be stored.

I'm reworking mine right now. (It's in my basement.) There used to be a place for a washer/dryer, but we moved that closer to our clothes near the bedrooms (upstairs) so it's almost a blank slate. There is a small earthen floor/stone wall closet I'm using as a wine cellar. I'm looking at an old fashioned sink/counter to put where the W/D used to be, so I can have a working sink and water supply. Across from that are wire (metro) shelves on wheels I can move if I need to, along with a clothes rack, also on wheels. (Those shelves store all the kitchen stuff that's too big or not used often enough, along with seasonal decorations in plastic bins.) It's set into a fairly large niche, and I'm planning on covering it curtains. All the paint, houseware tools/supplies are around the corner on shelving, and there's a work bench hung with florescent lights where I start seeds and keep plants during the winter months.

I think the idea of seeing what you have after grouping like items and going from there is a good one. I'm a fan of using anything on wheels, just so you can change the configuration and move items if you need to. I love the idea of pegboard for hanging things, if visual clutter isn't going to be a problem.

In my opinion it depends on what you'll be storing in there. As for the prebuild storage shelving I'd make sure if you are using plastic containers that they'll fit between the shelves. I've found there isn't enough height between shelves to fit the 18gal or 56qrt containers with the newer plastic shelf units. I have an older set of four units that I set two deep and two width where I can store either of the above mentioned containers.
Below is a sample of both types of shelves. I know it's messy. This was midway through a reorganizing of my fabrics and craft storage and I have a habit of making a mess when working. That way I don't miss a thing that needs tossed, but still keep the floor free for working.

Where is the storage room located? Is it on the main floor, where you could use it for storing things you use every day or is it tucked away in an attic or other corner where it would best be used for storing things you don't use all the time?

I could see a mix of shelving, with adjustable shelves if possible, with maybe a hanging rail for out of season clothes. And bins and other holders for out of season sports gear. An old chest of drawers for extra bedding--I think drawers work better than trunks or boxes for storing clothes and linens, because you don't have to dig to the bottom to find the one thing you want, leaving the entire bin a mess.

Have you considered the possibility of knocking out a place for a window and turning the room into something else, like a guest room, office, 3rd, 4th, whatever bedroom, or even a decadent bath? 11 x 13 is pretty big!