The same 50cm noggin will fit differently in various models because not all helmets follow the same internal shape. For example, the Shoei neotec is not as round of a fit (rather neutral between a narrow oval and round) as th shoei multitec provided.
With that out of the way-
I prefer modular helmets.
- I had an HJC- nice features, but it was kinda noisy. Not bad, but I figured there was something better out there.
- I had a Nolan N90- loved that helmet- especially the quick snap chin clasp--- I wish all helmets came with that. When it was time for a new helmet, I would have bought another Nolan, but I wanted to try out another fit.
- Now I have a Shoei Neotec. It is quiet (can hear pipes, music, and surroundings, but can't really hear any wind noise) and feels a bit more "plush" than my Nolan (this could be the newness) but it doesn't have the cool clasp. The placement of the latches and such don't seem quite right to me, but that could be because I still have the Nolan muscle memory. Shoei sells different cheek pads to fine tune fit, the ones that came with mine were like face squishers, so I ended up switching them out for a narrower pair.
All three of these are modular flip up helmets. All have an internal sun visor, ear speaker spaces, removable liners, and vent ports. The Nolan and Shoei were pretty good in regards to wind noise, and both fit my noggin shape a bit better than the HJC.
Webbikeworld has a big list showing their interpretation of the helmet shapes- plus all the other key stats and features for a number of helmet models.
