That's actually what I like with Thea: You can render on CPU and GPU at the same time with the Presto engine, so that neither sits idle. But it's especially cool with network rendering: When one client doesn't have enough GPU Ram or no powerful GPU at all, it automatically falls back on CPU (also quite efficiently so). And this also allows you to gradually invest in better GPUs whenever it suits you while Octane is a Yes/No solution.

And: Network render nodes are only 49.- Euro with Thea ;-)

There also is currently an introductory price for the Thea/Rhino Bundle including two network nodes for 320.- Euro
https://www.thearender.com/site/index.php/live-plugins/thea-for-rhino.html

All other engines are great as well of course, I just came to enjoy the flexibility of Thea for my line of work.
Whatever works best for you :-)

Cheers,

Tom