There are three main questions you will want to ask yourself when picking out an iPad model: How much of my music do I want to put on the iPad? how many photos do I want on it? Movies?
Surprisingly, the number of apps you want to install on the iPad may be the least of your worries. While applications may take up the majority of the space on your desktop or laptop, most iPad apps are relatively small in comparison. However, there are some apps, games in particular, that can take up a good chunk of space. Casual games like Angry Birds are usually very small, but games like Infinity Blade can take up to 500 MB or more.
The average song takes about 4 MB of space, the average photo around 500k of space and the average movie around 1.5 GB of space. This means a 16 GB iPad could hold 10 feature-length movies, 4,000 songs or up to 32,000 photographs. You could also store over 700 copies of Angry Birds on it, but only around 30 copies of Infinity Blade.
Don't forget about home sharing
Luckily, we don't need to load up our entire movie or music collection to enjoy it on our iPad. By using the home sharing feature on iTunes, we can stream our music and movies from our desktop or laptop to our iPad. The only requirements are that they both sign into the same home network and they both sign into the same iTunes account.
How to set up Home Sharing on your iPad
And since music and movies take up the bulk of space used by an iPad, this means the 16 GB model will be perfect for most people. Bear in mind that you will only be able to enjoy your entire collection at home, and if there are some rooms in your house that don't get a good Wi-Fi connection, you may not even have free reign there.
You can always load a subset of your music and movies onto the iPad for when you are out of the house. iTunes makes it easy to load a single playlist, and if you are going out of town, you can easily load a few movies onto the device.
But if you do have a rather large collection of music and digital movies, the 32 GB or even the 64 GB model may be more your speed, especially if you plan on consuming that media away from the house. And if you plan on using the iPad to play a lot of games, especially the high end games, you might want to skip the 16 GB version and go for the 32 GB version, though you can always opt for backing them up to iTunes and removing them once you are done playing.
Buy an Apple iPad 2 with Wi-Fi - 16GB - Black
I'm still unsure which model to purchase
If you are a frequent traveler, the 32 GB iPad is a great balance between storage space and elbow room. But for most people, their heaviest iPad usage will come in the home, and for them, the 16 GB model will be fine.