I would check out the Shoei Quest (round to med oval fit). These are a highly rated/reviewed helmet on clearance most places online right now at up to 50% off. Shoei is in the process of replacing the Quest model with an updated model so it is a great time to buy heavily discounted old stock. Bell helmets can be a great choice if you have a longer oval head shape.
Helmets will vary considerably by the head shape they fit optimally, the ventilation they offer, weight, comfort, safety, crash protection certification, convenience features, price and graphics. The only way to know what is best for you is to try on lots of helmets and do lots of reading. Unfortunately you can't judge things like ventilation and noise in he showroom but 4 front vents will be better than 2 and multiple exhaust vents are better than 1.
Fit generally puts you in one of three categories between the extremes of a long oval head shape (long from front of head to back of head in proportion to head width) and the round headed (many Asian people). Check out www.webbikeworld.com
My personal preference is for mid priced FF helmets (~$400 range). You get a lot of features of the high end helmets (~$800+) at a lower price point and I don't need an ultra light carbon shell but they are a lot cooler, more protective and comfortable and lighter than than cheaper helmets (~$200). Things like better ventilation and more accurate fit and higher safety ratings. WRT safety ratings look for Snell 2015 or ECE ratings. Do consider purchasing a dark tinted visor with your clear visor as these are really nice
to have on a sunny day, and don't have the sometimes compromised safety, restricted venting, and increased shell size issues of a helmet with a drop down inner visor. Pinlock visors are amazing if you ride in the rain or cold as they are about the only thing that completely eliminates fogging.
Although you can't always see the difference in construction, cheap helmets use a single thickness of ABS throughout in the plastic shell and a single type of foam for shock absorption. As the price goes up you start to see composite laminates of fiberglass and Kevlar and other exotic fibers of varying thickness throughout the shell that is locally stiffened in certain areas of the shell that require it and different foam densities of layered foam under the shell for shock absorption. Also things like cheek pad thickness may be altered for a customized fit.
Hope my brain dump on the subject is helpful.