Which combination is the best practical synthesis of ethyl tert-butyl ether, (CH3)3C-O-C2H5, in good yield?

Williamson synthesis proceeds by $\mathrm{S_N2}$, which needs an unhindered (primary) alkyl halide. With $\mathrm{C_2H_5ONa}$ and tert-butyl bromide, the alkoxide acts as a strong base and the tertiary halide undergoes E2 elimination to give 2-methylpropene. Using tert-butoxide with the primary halide ethyl bromide gives substitution. Dehydration of a mixture of alcohols gives a mixture of three ethers ($\mathrm{Et_2O}$, $t$-$\mathrm{Bu_2O}$ and the unsymmetrical ether), and tertiary alcohol mostly dehydrates to alkene.