Tablets for sure. There are no good coding apps on Tablets.
Say you're going on a trip somewhere and don't feel comfortable bringing your $3,000 laptop. Pickup a $150 android tablet + keyboard. Or low income individuals, you could start coding right from your phone without having to buy anything new.
There a couple of nice coding apps in Android and iOS, naturally they are mostly for coding on the train/plane, or tying out ideas at the local coffee shop, but that is good enough for me.