Not sure who would win here, so I'll list them side by side. LAFC won the most recent MLS Cup, meaning they've officially dwarfed LA Galaxy on the field. Since Zlatan left, it's actually been LAFC that has signed the likes of global stars like Giorgio Chiellini and Gareth Bale. If LA Galaxy wants to return to its glory days in Los Angeles and the MLS, where they signed the likes of David Beckham, Steven Gerard, and Ashley Cole, they'll go all out for Ronaldo. From the perspective of LAFC, they have a couple of Ronaldo's high-profiled former teammates in Bale & Chiellini, which bodes well for their chances, as does the fact that they're on the upward trajectory in reputation compared to LA Galaxy's downward trajectory.
The downside here is this would be throwing in the towel. No more European football, no more high-profiled Champions League games, and the end of his time at the center of the footballing world. They can for sure afford his wages, but this is the ultimate calling-it-quits move as he joins a league slowly migrating from its reputation in its formative years as a retirement league for washed-up European stars.