Disclaimer
I work at a shop, yes, but am not trying to sell you anything, just providing my two cents.
I’ve used Giro in the past and find the fit very good. Currently I am using a Specialized Tactic II with MIPS technology. I find the Specialized helmet has the best fit for me, overall. I did have the opportunity to get a less expensive helmet this year and paid extra for the Specialized.
The MIPS technology is fairly new for bike use. However, the research does indicate that it helps decrease torsion in the case of direct impact. The helmet is more expensive due to the technology, and the helmet is still one hit only. I hope never to test the theory personally.