I have LR6 also, I bought it after I dropped my CC subscription. I just do not like the subscription model. I set about looking for a suitable alternative to Photoshop *and* Lightroom, and I believe that the current version of Photos plus the many plugins it now can access is more than adequate. You can do basic editing in Photos, and I do, sometimes, but more often than not will use an external editor. Acorn (Mac only) is the closest to Photoshop in function that I could find, but its not well known or particularly popular... it does the job for me. I also have the MacPhun apps which are coming to Windows soonish as well as the Nik Software which still requires an adobe product or Aperture to be able to install, even though they can be used as standalones. Mind you, Google is killing Nik pretty soon so if you want it, you should get it. Its free for all users. Anotehr Photoshop alternative is Affinity Photo which has now also been released for iPad. Its available for Windows, too. And then, theres the OnOne Photo Raw which is excellent, albeit with a butt-ugly GUI.
Linkies:
http://www.macphun.com
https://affinity.serif.com/en-gb/
https://www.google.com/nikcollection/
https://www.on1.com/promo/0617-photo2017/
Just went back to the OnOne site to review the 2017 version and am seriously considering upgrading from my current version 10.5, the price isnt bad at the moment, and it does play nice with Lightroom. If you visit and note the free listing (menu at top of page) you can get a free version of Effects. Might be worth grabbing that, and the trial of PhotoRaw 2017. I must confess I have not been able to adapt to Affinity (I was in the beta trials) and so have not purchased it. Many seem to love it, and its extremely powerful, no doubt.