RS31 is cheaper and faster, Aksium has the advantage of better sealed (cartridge) bearings but the disadvantage of FTS-L freehub. On balance, pulling the Mavic freehub off every time it gets wet is probably easier than regreasing the bearings on the Shimano wheels under the same circumstances, so I'd take Aksiums for all weather riding, but for a fair weather racer the Shimano wheels have it.
If you want something stiffer/stronger/cheaper and only slightly slower, R501-C30 does essentially the same thing as RS31 with 4 extra spokes per wheel.
You need to spend £550 on Zipp 30s (which is 4 times the price of RS31s) to make a worthwhile step up from budget wheels.
RS31 is cheaper and faster, Aksium has the advantage of better sealed (cartridge) bearings but the disadvantage of FTS-L freehub. On balance, pulling the Mavic freehub off every time it gets wet is probably easier than regreasing the bearings on the Shimano wheels under the same circumstances, so I'd take Aksiums for all weather riding, but for a fair weather racer the Shimano wheels have it.
If you want something stiffer/stronger/cheaper and only slightly slower, R501-C30 does essentially the same thing as RS31 with 4 extra spokes per wheel.
You need to spend £550 on Zipp 30s (which is 4 times the price of RS31s) to make a worthwhile step up from budget wheels.