Not taking money into account I too would go for the Fulcrum's... Both wheelsets RRP at around the Â£200 mark. However, I can get the Aksiums for Â£80. So, could anybody tell me whether the Fulcrum's represent a Â£120 difference?
I hate my two pairs of Aksiums, I really do...but, I just can't kill them. So props where they are due. I train on them because they came as OEM components on a couple of bikes I bought. Not the lightest, not the most aero, but pretty damned bomb proof. Black or silver, I've even learned to live with the somewhat cheap decals and graphics. Mavic's warranty/internet rep seems to be very good, although I've had no need of it so far.
The hubs are fine and untouched after about 8,000 miles on the one pair. Mavic uses ABEC Class 3 bearings with double seals. Pretty good specs on a low-end wheelset. I did touch up the spokes after the first couple of rides bedded them in. No big deal.
The wheels are on the flexible side, but just about all the 'modern' 16-24 spoke wheels I've ridden are.
Fulcrum is good stuff with the Campy-Cool factor. The 5's are excellent wheels. The only negatives I've heard about Campy/Fulcrum wheels is that the G3 spoke layout go out of true from new. Again, no big deal. Freewheel and hub hardware is typical Campy...top quality. The 5 uses the same bearing retention setup as the Aksium. Disassembly and service is old-school simple.
Mavic spokes are easier to come by in my area (but so is shimaNO stuff), but as long as you stock a couple of each length needed in the toolbox you're good to go. Both factory warraty specs are almost identical, with Mavic offering the MP3 extra cost protection policy (dubious for a lower end product, but it is there if you want it on new purchases at least).