Answer
Engine 1.
Work Step by Step
We know that thermal efficiency is given by
$$\eta=\frac{W_{\mathrm{out}}}{Q_{\mathrm{H}}}$$
where $W_{\rm out}$ is measured by the enclosed area of the cycle.
And since engine 1 has twice as much enclosed area as engine 2.
$$W_{\rm out,1}\gt W_{\rm out,2}$$
then the thermal efficiency of engine 1 is as twice of engine 2.
$$\eta_1\gt \eta_2$$
