At near sea level, the drag at those speeds is absolutely brutal. Airplanes win, although they’re harder to electrify.
If you extrapolate current Maglev designs to 1000km/h, for energy consumption per passenger mile is about 0.5kWh/(passenger-mile).
Airplanes are on the order of 100mpg/passenger, or 0.33kWh/(passenger-mile) even with the relatively low conversion of chemical energy to mechanical in a jet engine. An electric aircraft could get about 0.1-0.2kWh/(passenger-mile) with the same airframe if the battery chemistry is appropriate for that flight length. Improve the airframe, and <0.05kWh/(passenger-mile) is possible.
Length of electric flight is limited, but 1000km is possible with current chemistries. America’s near-term HSR routes are on the order of 500km, so electric flight is feasible.
This is why “Hyperloop” (or vacuum trains generally) are and were a good idea at the high end for high speed rail, in spite of all the mocking that Elon Musk incurred for the idea (which he/SpaceX popularized and funded student competitions for, although the idea is an old one). Otherwise airplanes win on efficiency.