A few hopefully helpful comments from another Peter:
First, it’s essential to be realistic about what hearing aids can and cannot do (and I’m referring here to conventional behind-the-ear units, not surgical implants, etc.). While I salute Dave’s experience, it seems unrealistic to expect any such device to fully restore your hearing. Modern units can work wonders reducing background noise and boosting frequencies that have become weak. But generally speaking, if frequencies are completely gone, they’re probably gone for good. You can quickly get an idea of your degree of high-frequency loss with an old hi-fi test record or on-line sweep tones. (Do each ear separately, though, by blocking the other.)
At $6K per pair I’m in no position to compare brands so I can just speak of my limited experience of a few months with Phonak. (Consumer Reports published an article in its June issue that has helpful background info but its survey comparing user satisfaction with various brands seems pointless, since reaction is entirely subjective and most users presumably had no wide-spread experience.) Much to my surprise, insurance paid nearly half, which brings the cost down to something closer to reasonable. Vets may do even better, so do check.
My loss is fairly mild (so far) – nothing above 6k or so, a few annoying resonances below that, mild tinnitus and increasing difficulty understanding speech – but the aids definitely help. Be sure your audiologist lets you try whatever pair he/she recommends for at least several weeks before you have to commit to buy it, since results are quite variable and may not meet your expectations. And do use an experienced audiologist - this isn't something you can do on line.
I used a 1/3 octave equalizer to isolate the frequencies of concern to me; that helped my audiologist customize my adjustments for music.
Phonak allows you to toggle among several different settings, each of which can be adjusted for volume within (I think) ten frequency bands, so you can customize them for speech, music, TV, etc. For me, a high midrange boost is good for conversation while a boost of higher frequencies helps for music.
Phonak (and, I assume, other brands) has an accessory that plugs into the audio output of a TV and lets you get the sound directly in your aids with Bluetooth. The result is much more intelligible than amplifying sound from TV speakers and room ambience – well worth the extra $250 or so.
Phonak has an app that enables your audiologist to adjust the aids remotely using a Bluetooth link to your iPhone. This is essential, as it lets you try out a setting in your home environment, request a specific adjustment, try the new setting immediately while he/she is on the phone, explain your reaction, tweak it some more, try that, etc. – far better than having to go to an office for adjustment, go back home, try it out, remember your reaction, go back to the office, and repeat the process multiple times. You can achieve results in a half hour and with far greater precision than countless hours of back-and-forth travel and inconvenient office appointments would provide.