It's all about the HYPE! The NEW Malossi is a safety bell that will capture shrapnel if the clutch explodes. That is the best bell you can buy. Bells like the Nakaru are built with the same steel/methods as the OEM. Some have a second "skin" applied on top for looks. The Stage 6 MKII is an actual milled piece vs stamped steel. I haven't run it yet but it appears much stronger than OEM/Malossi Delta. Unless you have a specific design, or use for the scoot any of the top brand bells are fine. Just stay away from ebay/cheap/China replacements. These are common stamped steel, and have very little strength. The welds are "spot welds". One weld cracks, and the bell goes where it wants.
Just to top it all off... I prefer the bells with fans built in, and the lighter the better.