.243 is a pretty darn good deer/antelope cartridge. Depending on demographics, you'll usually find .243 ammo more readily available regarding selection compared to 6.5x55Swede. Not that stores don't have any 6.5x55, just .243 usually has more variety. Reloading for .243 isn't difficult and there's recipes abound. It will be a little bit cheaper to reload than the 6.5 if you're cost conscious.
HOWEVER, if you're looking into hunting anything larger or want to get semi-serious on target shooting, my choice is the Swede. At longer ranges, accuracy is the Swede's forte as well as being capable to take down any North American game and still have mild recoil. Reloading recipes are quite adequate and the cartridge is very forgiving.