After shooting a .17 HMR, I think I'd go that route. I have a Mach II (Kimber) and while it's accurate, it isn't on the accuracy level of the HMR, and the HMR can reach out a wee bit farther, and has (or seems to have) less wind drift than the Mach II at 100 Yds.
The .22 Hornet has one advantage, it's reloadable if you reload, therefore, if you reload, it can be loaded for different power levels.
