The first thing I'll tell you is that fundamentally they're all pretty much the same. In general they're all made with equivalent components and the only real difference is Bells and Whistles. It's the only thing the companies can do to differentiate themselves from other manufacturers. Unless you've got some special type of loss, a basic simple model will probably work just fine compared to something fancy. The biggest choice comes down to size and how self-conscious you are about it. Generally, the smaller they are, the weaker they are and more expensive. You're paying for vanity.
You can probably forget about insurance covering it. Almost no health insurance will cover them. They're considered non-essential, "cosmetic" devices. My company provides very good health insurance and only once over the past 30 years have they ever covered -any- of my hearing aid purchases. 11 years ago (during the dot.com boom) I actually had a company cover part of one ( $1000 of a $2800 purchase ) but that was an anomaly. If you're lucky they might cover the hearing exam but considering most places give you that free as part of the purchase process it doesn't do much good. I've had a couple insurance companies tell me "no we don't cover them, but we offer these great coupons" which were basically a 25% discount off of something that was marked up 100% to begin with.
The most important thing I can tell you is to get a Costco, Sam's Club, or other shopping club membership. I have a Costco membership and have bought my last two sets of hearing aids there. They were 1/3 the price that I was charged at regular hearing aid stores. Costco had audiologists that were just as qualified as the regular stores, and sold the same models/manufacturers as the regular stores. As an example, my last "hearing aid store" model cost $2800 in 1999. The three I've bought since then ( the last two a couple of years ago ) cost $890-$1000 each and were far better than the $2800 model.