AX? DE? Both? For DE I'd want a full face. Do you wear glasses? Then you need a large eye port. The most important thing is you need to try them on. Even if the size is the same, they will fit differently.
I went with one of these - https://www.bellracing.com/Shop/Product/M8-Carbon - You're paying extra for the lighter-weight carbon-fiber construction. Lower price points are the M8 (a bit more ventilation with 3 head vents, larger eye port, etc.), Evo (larger eye port), and baseline Sport. This is the factory in Illinois, in years past talking to them they were good about exchanging a new helmet if you found it didn't fit right when you got it. If you don't have any place to try on & sample the fit for what you're looking for, I'd figure a conversation with any seller to help with figuring sizing & clarifying their policies would be a good idea. https://www.bellracing.com/Shop/Category/road-racing Racequip Pro 15 here might be the Snell SA bargain helmet out there - https://racerpartswholesale.com/race-drivers/helmets/?sort=pricedesc&_bc_fsnf=1 Racer Parts Wholesale used to carry G-Force, looks like they dropped them - http://www.gforce.com/category/helmets/snell-sa2015-helmets/
