I used to use MORE 3.0 and it was so powerful an outliner document maker but then it went the way of the dodo bird. I use OmniOutliner a bit but only the basic one as I seldom write anything lately, except letters and then I mostly use Daylite a CRM that I have used for 20 years after CAT, when away as well on the Mac. It sucks in the emails into itself so you can keep track of every email, letter etc. Great program but now they want a subscription yearly and I don't want to buy it so I bought a new mac and I froze the OS to High Sierra for the next 5 years.
Subscription services may be there only moneterizing way to live but if your not in business any longer the cost adds up for little use.