No matter what you’re trading, I think you should go with a small tablet.

Unlike large tablets, desktop PCs, or laptops—which are all heavy—you can just put it in a small bag and carry it.
And unlike phones, with their tiny screens that are uncomfortable to watch.
Figure 1: small tablet; Figure 2: candybar phone—it's a world of difference. No matter how I adapt, with a screen that small, there’s simply no room to fit anything.