Here are 2 different page builders for WordPress that fill 2 different needs.
Thrive Architect is ideal for creating single pages, landing pages, etc, where Divi is better at creating entire websites.
The feature set that comes with Divi, like their header/ footer builder, style-sync, etc, are just better for full site builds.
On the flip side, Thrive Architect has modules that are very equivalent to Divi, but some better for marketing.
A perfect example is timed content, countdown timers, popup boxes, etc.
Also, Thrive Architect is part of a larger family of plugins that all work in perfect harmony, much like Apple devices.