Might as well through my 2 cents into this. I am what I consider an "advanced amateur" and have been shooting primarily RAW for quite a number of years. I was an Lightroom user till I moved to a Mac and then fell in love with Aperture. When Apple (in their infinite wisdom) decided to stop it's support for Aperture, I first went back to Lightroom because initially Photos just did not give me enough tools. Now with the various extensions I have gone full blown into Photos, and aside from some limitations (needs a better search engine and the ability to import RAW+JPEG as separate files so you can delete the one you don't need), I have been very happy. I have been able to do 90% of my adjustments using the built in tools in Photos and the few extensions that I like. Otherwise I have Affinity Photo but have been learning Pixelmator again just because it's a bit simpler and enough for my needs.
There is a great app called External Editor, which basically makes it very easy to work on any photo in Photos using any photo editing program you have on your computer. But the way the files are sent back and forth from Photos varies, so you have to play around and see what editor works best for you.
Also, someone mentioned RAW Power, which basically gives you all the sliders and adjustments that were available in Aperture that did not make it into photos. (From what I read one of the developers actually worked on Apple Aperture.) It works very well - for the time I tried it out - and if you need more controls for your RAW conversions, it has much more adjustments than the Photos Edit panel.
There is a great app called External Editor, which basically makes it very easy to work on any photo in Photos using any photo editing program you have on your computer. But the way the files are sent back and forth from Photos varies, so you have to play around and see what editor works best for you.
Also, someone mentioned RAW Power, which basically gives you all the sliders and adjustments that were available in Aperture that did not make it into photos. (From what I read one of the developers actually worked on Apple Aperture.) It works very well - for the time I tried it out - and if you need more controls for your RAW conversions, it has much more adjustments than the Photos Edit panel.