I without a doubt prefer Bitcoin. Ethereum is a nice world virtual machine, but for holding money, the array in crypto-currencies that interest me the most, Bitcoin is probably better suited, thus my preference.

GPU mining will last as long as it will be profitable. When there will be too much miners, the difficulty will drop, and more will join. At some moment there will be an equilibrium that will rise and lower.

There is actually only two possibilities for tokens : Ethereum ERC20 and Waves, and from the two I largely prefer ERC20 ones.