If 1000 yards accuracy, fun, and statement, is your goal, I would say mag fed is a must, be it semi or bolt action.
The Steyr HS-50M1 is a capable gun, but somewhat lame in the design department if you ask me. Side mounted mag is so 1950s.
PGW50 is a great option, fun as hell to shoot and seriously accurate if you provide the right ammo.
The semi auto Serbu .50BMG is a great plinker, and amazing to look at and operate, providing you spend a few bucks on a competent gunsmith to tune it to the ammo available in Canada.
The Steyr HS-50 Platform, whether the single shot or the bolt action, is very accurate, and well designed. Just watch out how much torque you put on the bolts that hold the barrel on. (you need to disassemble the rifle for transport.) I have stripped them once through regular use, and needed to take it to a smith to take them out and replace them.
The Windrunner I have no experience with, but it seems to be an upsized .408 cheytac platform. I defer to more experienced users here.