I have a bunch of helmets in my collection, full face and modular. As I look around I see a Schuberth, an Arai, two Nolans, and a Scorpion. Some are supplied to me for various product tests I do, others I've purchased with my own dough.
Of all the ones I have, I like the Schuberth C3 Pro modular best. Light and comfy, nice to be able to set the internal visor at any position (not just deployed or retracted, as with the Nolan and Scorpion), rachet type closure. One drawback is the airflow through the helmet isn't that great, especially with a fully faired bike. I bought this with my own money and I'd buy another one.
For full face I like the Arai Vector Air, which has amazing airflow, including two little vents in the visor. Also light, comfy (Schuberth is better). I wish the Schuberth had this much airflow, but I prefer a modular.
The Nolans (N102 and N103) are right up there with the Schuberth for functionality, fit and finish, etc., but side-by-side Schuberth is a notch above overall. More expensive, too.
The Scorpion is OK. Doesn't fit my head shape very well so not that comfy. Has an internal sun visor. Examine it next to a premium lid and the difference in quality is apparent. Still DOT approved, so it should protect your head to the extent a helmet can.
Regarding built-in Bluetooth, I was disappointed with the BMW Bluetooth system designed for the Schuberth. Sound quality sucked, it only worked with BMWs and one other rider (who had to have the same BMW/Schuberth system), no bike to bike. I uninstalled it and sold it (to someone who was thrilled to get a gently used system for less than a new one), and got a Sena 20S which is better in every respect.