Typically, the Wi-Fi Only model is sufficient, in my opinion, but it's nice to be able to use the device when you're not able to connect via Wi-Fi. As for the storage size, 256 GB is way more storage than a majority of people actually need, in my opinion. I mean, unless you're planning on storing a massive quantity of video, photos, music, apps, games or other data, you should be able to get by with 64 or 128 GB easily.