If you truly want the best quality way to get negatives into digital files, a dedicated film scanner is specifically designed for the job, and works better than a flatbed scanner. The Nikon Coolscan scanners are not mid-level, they are professional quality devices, yet not hard to use. They used to be very expensive, but not as bad now- search on-line. I have had both Minolta and Nikon film scanners, and they allow you to get great scans from either negatives or slides whenever you need them. As with so many things digital, the newer the scanner, generally the better the dynamic range, and the better scanners have Digital ICE, a feature that can automatically retouch out dust, scratches and fingerprints. I use it all the time and it really works.
If you don't want to buy a film scanner, another option is to send them to a pro, although you said you want to do your own scanning. Doing your own means you do not have to send your irreplaceable negatives out, and you have much more control.
If you already have a good flatbed scanner with the special attachment for scanning transmissive items, like slides and negatives, that will work and may be good enough, but it has to have the special backlighting device for scanning film, or the scans will not be very good. Most flatbeds are designed for scanning reflective items, like prints. Only the high end ones have anything like Digital ICE. I have an Epson Perfection scanner that has the special device and Digital ICE, but I still prefer the film scanner for negatives. It is easier in the end for me.
Whatever scanner you choose, good scanning software also makes a difference. While you can use whatever ships with the scanner, it may not be the best software. I have been using ViewScan for years and recommend it. It supports hudreds of scanners, gives high quality results, and is easy to use. See the link below. There is a free trial period.