What is the best hearing aid for a reverse slope cookie bite loss?

It is my humble opinion that there really is no "best" hearing aid; however the best device is one which is properly programmed to fit your needs.   All of the major hearing aid manufacturers have  technology which can be adapted to fit most hearing profiles, including what you describe.  I strongly believe that the provider you choose is more important than the product.  The right provider will make sure that your needs are addressed.

There is no product that we can say is "the best" as ultimately it is a personal decision. Some individuals prefer one manufacturer and other may prefer another manufacturer or another model. Still, I will say that many individuals that I know have a preference for oticon aids for RSHL but again, that does not mean it would be best for you. I would add that the most important factor should be choosing an audiologist who has a good understanding of reverse slope or cookie bite hearing loss (btw, revere slope and cookie bite are two different configurations of hearing loss...do you know which one you have?). It is important to not only understand the numbers on your audiogram but to ask your audiologist to perform other tests such as speech in noise testing or the TEN test to look for dead regions. In general when we program the hearing aids for reverse slope, it is important not to add too much gain in the low frequencies that could potentially mask important auditory information in the mid and high frequencies. You dont have to worry about the specifics in programming as long as your audiologist does;) 

Interesting question!  Reverse slope and cookie bite loss are typically looked at differently as they are not the same thing.  Perhaps you mean reverse slope in one ear and cookie bite in the other.  Nevertheless, opinions on the "best" hearing aid for either type of loss will vary greatly among health care providers.  Honestly, most manufacturers have products that will address either of these types of losses.  What is most important is that your provider can confidently address the needs, regardless of the loss, and will work closely with you to maintain the aids for your best audibility.  As a rule of thumb, difficult losses usually require more advanced features that allow more control and better adaptability.  Don't be shy in asking about the various options and be sure you understand the whys behind the recommendation.       

From more of the technical side, treating this hearing loss with any manufacturers hearing aid is complicated.  Depending on the severity, in order to get amplification in the low frequencies, you would have to occlude your ear.  You would then have to process sound for the mid-ranges that you may have normal hearing in. Then amplify the high frequencies as well.  Of course, you always have the option of not amplifying the low frequencies, leaving an open vent for the mids, and still amplifying the highs.  Essentially, answering this question well really depends on your hearing loss, and your perception of the way things sound when you are fit.  As long as the fitting concepts are well thought out, you have a shot at receiving benefit from most hearing aid brands and styles.

Most all of the major brands will adequately handle this type of hearing loss.  A higher technology level aid will do a better job of more precisely matching the loss itself but the bigger issue is finding a provider who is very good at fitting a reverse slope.  it is very easy to over amplify lower frequencies which mask the higher frequencies needed for clarity.  In that case you would experience good volume but a lack of understanding.  80% of the value of your fitting will come from who is programming it.  Only 20% of the value comes from the hearing aid itself.  

I would look at ChannelFree technology from Bernafon, which seems to suit a cookie bite, especially with the new Zerena's. 

I agree with the majority of what has been said, definitely find a provider with lots of varied experience who you trust.  Make sure you understand this is a process, often times people with complicated hearing losses or who are new to hearing aids will think the hearing aids are wrong for them because they are not an instant success.  Any hearing aid fitting should involve adjustments and reprogramming a few times to get it right, we are all individuals and no two people have their hearing aids set the same.  In terms of hearing aid recommendation, any manufacturer would be an option, but I would suggest a hearing aid with a custom ear piece (in the ear or behind the ear with custom mold) rather than a RIE/RIC style.  In my experience it is difficult to get that much low Hz amplification from an RIE/RIC.

Almost all hearing aids now are programmable so your hearing test is actually downloaded to the hearing aid and therefore adjusted accordingly. You don’t need to go to the top of the line but don’t go to the bottom either. When you have an out of the ordinary hearing loss, it is easier and more satisfactory to have more channels in order to really pinpoint your loss.