Below is a list of addons that the author of the site uses. None of them are recommended over and above any other addons, and this shouldn't be viewed as a "recommended addons" list. They are purely a list of addons that one individual uses to assist with maintaining and managing a guild, running raids and every-day playing of World of Warcraft.
The majority of these addons were, originally, all downloaded and updated from Curse, however as can be seen below, can also be found in other locations if you do not wish to use the Curse manager.
Please note that Curse (Overwolf) now currently offers two different download managers - one is their standard "full" offering which has a lot of other utility other than just a download manager, but will not work on Linux systems. They also have an "alpha" of a cut down version, which is a pure download manager, which will work on Linux (and other OS's).
The author uses WowUp (you can download that here: https://wowup.io/ ) which allows you to keep addons updated from multiple locations, but not Curse (hence the list below!).
*Edit - since the time of writing this, WowUp and Curse have collaborated to create a new WowUp addon manager that can maintain your Curse addons. There is a tradeoff in that this version of the addon manager must be based on Overwolf/Curse's own manager and software, and does not include Wago support. The original WowUp (maintaining addons from all the locations other than Curse) is still available, will continue to be maintained, and does not include any input from Overwolf/Curse.
This list is not exhaustive, was primarly created for personal use and, especially for those addons showing links outside of Curse, may well have more than one download site available. For those where there were various sites, if they were all the same version, I've just picked one - otherwise I've checked for the more up-to-date version. These are retail addon links.
If you wish to use these addons on WowUp, for some, you can simply use the "Get Addons" page and search for them. Addons that are on Wago, Tukui or WowUpHub should automatically be found. For the others (other than curse), you should be able to copy and paste the url below using the "Install from URL" button on the "Get Addons" page in WowUp. Once on your addon manager, they should automatically update when the author updates them on that site.