When you start shopping around for your iOS devices, you have to take a lot of things into account. But the biggest factors when making such an important purchase is to consider your use cases and what size is going to suit you best.

When I mention the size of the device, I don’t mean just the physical size of the device itself. I also mean the size of the storage within it.

I’ve had many iDevices over the years, and I’ve found you need to look beyond price and decide what you’re going to be using the device for so that you don’t wind up with buyer’s remorse.

(And, yes, even though Apple products are both elegant and of top quality, you can experience that feeling if you don’t assess your needs before pulling out your wallet.)

There is one thing that is ubiquitous across iOS devices—range storage sizes. Each model has its different storage capacities and what you are going to put on the devices needs to be strongly considered, not forgetting to keep syncing in mind as part of the equation. The storage capacities for the current models of iOS devices are as follows:

• iPod Touch: 32 GB, 64 GB
• iPhone: 16 GB, 32 GB, 64 GB
• iPad: 16 GB, 32 GB, 64 GB (iPad 2 only comes in 16 GB…steer clear at this point)
• iPad Mini: 16 GB, 32 GB, 64 GB

First off, if you are only going to be picking up one of these devices and you have no intention of picking up another to complement it (ie. iPad and iPhone), then when you are making your decision you should still keep in mind the amount of storage you’re least willing to live with. You want to do this for a number of reasons.

You may decide to buy a companion device at some point if it fits the needs of where you’re at. Since the refresh cycle on Apple products can vary, you may want to steer clear of the lowest capacity just in case the next model of companion device you’re going for exceeds it when it goes to market. This might not be a problem for you if you’re not storing tons of photos, videos, or audio on your device, but it can wreak havoc with syncing down the line if you do.

Regarding syncing, the iPads and iPhone models have capacities of 16, 32, and 64 GB. Ideally you would want to pair up a like-sized iPhone with a like-sized iPad. The reason: ubiquity.

If you have an iPad that has less storage then iPhone and you’re using an app that allows for syncing across devices (like Rdio, for example), you may run out of space while syncing. You will never quite know what is on one device and what is on another. This idea also works for writing apps like Byword or photo apps like ThisLife. Ubiquity gives you peace of mind. It doesn’t matter what size you buy – you could go with the least expensive option for both – but if you are using your devices for media and iCloud syncing of any sort, then you should go with like-sized storage across all devices.

Another thing to look at is what you actually plan to use the device for. This is when physical size comes into play just as much (if not more than) storage.

For example, I’ve been pining for an iPad Mini. I do consider it to be the best platform for productivity, and that has been one of the reasons why I’ve been looking seriously at it. But I also spend a lot of time writing on the iPad I have now, which is an original iPad. Now obviously I’m not going to see any difference in the displays between the two, and the storage would be the same as I have a 32 GB iPad now. And since I use my iPad for reading, the form factor of the iPad Mini would be more ideal. Not to mention the price point for the iPad Mini is more appealing.

So why am I hesitating?

I’m hesitating because I really don’t think the screen size on the iPad Mini is conducive to the amount of writing I’m used to doing on my current iPad. That’s become the deal-breaker. It’s for that reason that it looks like the iPad 4 is going to be my new iPad.

How you are going to use these devices will play a huge role as to what device you choose. Here is a guide for each of the iDevices so that you can quickly see which one is right for you based on your particular use cases.

iPod Touch

• You don’t need a smartphone
• You like to work out to music
• You like to listen to podcasts while you commute
• You like to play games

iPhone

• You need a smartphone
• You want to be more productive while on the go
• You don’t like to carry a lot of devices with you
• You like to work out to music or listen to podcasts while you commute
• You like to occasionally play games
• You spend quite a bit of time on social media
• You could really use a GPS

iPad

• You want to have something that can act as your main computer while you are on the go
• You give presentations while traveling
• You like to read e-books
• You want to more productive while on the go
• You don’t need a smartphone
• You like to write extensively while on the go
• You don’t have an iPad Mini

iPad Mini

• You don’t need a smartphone
• You like to read while on the go
• You want a device that can act as your main computer in a pinch
• You want much of the iPad functionality but for less money
• You want to be more productive while on the go
• Having Retina Display doesn’t really matter to you at this point
• You don’t have an iPad

As for the choice between wi-fi and 3G/cellular, I’m of the mindset that unless you’re travelling a lot, there’s no real need to get an iPad that has cellular as a feature. I have the 3G version of the original iPad, and I have rarely used the cellular connectivity that it is capable of handling. If you’re ever stuck and need it, simply tether your iPhone instead. That’s what I’ve done and it works like a charm.

My needs are going to be different than yours. In fact, my needs are going to be different than many. I’ve weighed all of my options, including platform and storage size. And I can confidently tell you that with my iPhone 4S still doing the job and my original iPad slowing to a crawl, I’ll be getting an iPad 4 wi-fi with 32 GB in the near future.

Ultimately, when you’re looking to decide on an iOS device, it boils down to who you are as a user — and not much else. The 16 GB models are only an option for only the most casual or budget conscious, the 32 GB models are generally great for everyone, while the 64 GB versions are for the heavy media and “app crazy” user. You need to figure out what type of user you are. You need to size yourself up first, because when you size things up before getting your latest iOS device, you’re setting yourself up for a better user experience.

Photo credit: Yutaka Tsutano (CC BY 2.0)