I spend many hours in the last 2 days researching all the various directory platforms and I decided that Brilliant Directories was the best of the bunch for my use case.

Read the online reviews and comparison and you will probably reach the same conclusion. For example, compare https://www.capterra.com/p/133173/Brilliant-Directories/reviews/ to https://www.capterra.com/p/149786/eDirectory/reviews/ .

Regarding competition with WordPress themes and plugins, there are many mentions of users switching away from WordPress because of the larger number of features in Brilliant Directories and the seamless integration of the plugins.

I just wish the company did not play games with pricing the way they do. If you google, you can find references to past coupons for 30%, 40%, 50% and even "up to 90%" off discounts during Black Friday 2020. Using their current coupon "GET350" reduces their list price of $1,450 down to $350. It gives me a bad feeling when companies have sky high prices but constantly offer a large range of discounts which gives me that "doubt" that I am getting a good deal compared to others.

I decided that $499 for AppSumo Tier5, that includes the bundled addons not included directly on their website for $350 (after applying "GET350") was a better option for my use case. This is especially true since they are offering to double limits for a review on AppSumo that then equalizes to the 100,000 member limit.

I'm also probably going to purchase the 3 website bundle directly from https://www.brilliantdirectories.com/directory-discount-club that ends up costing $487.50 after applying the 75% off coupon you get with Tiers3-5. At a cost of $162.50 per website, I think this will also be a better option because even though Tier1 is only $89 at AppSumo, Tier1 only includes 250 members instead of 100,000 and also does not include "Developer Tools" that is included in their 3 website bundle.

"Developer Tools" is required for implementing standard features offered by competitors ("Robots.txt File Access, HTACCESS File Access, 301 Redirect Management"). And it is required for complete customization ("Access to edit default HTML, PHP, CSS & JS widgets and page template code, Create your own code snippets: HTML, PHP, CSS, JS"), database management ("MySQL Database Access, Remote SQL Access"), and integration via SyncSpyder ("read and write to your database from 3rd party apps, tools and websites").

P.S.
Since they host all their customers' websites, you can discover many of the websites using this SaaS by doing a reverse DNS lookup... https://viewdns.info/reversens/?ns=NS1.DIRECTORYSECURE.COM

Use this list to checkout (before you buy) how others have customized the platform, run speed tests against them, and analyze technical SEO of the platform.