The only way to know is to try streaming to an ingest and see how the quality is.
The Ingests API Reference | Twitch Developers will include the “name” of the ingest and that name usually refers to a geographical location
Broadly speaking a streamer would want to broadcast to the nearest ingest geographically.
There are also other extenral tools and OBS itself includes a tool to test ingests and see what works best. (stream for a bit in bandwidht test mode and monitor bandwidth and dropped frame counts)
So the only way to find the best is to test and see how it goes.