oh man, I totally feel u on this one. I've been shooting with the 90D for years and that built-in flash is basically useless for pro-looking stuff. In my experience, the Godox V1-C Flash for Canon is the absolute best move for your $250 budget. While the Canon Speedlite 430EX III-RT is a classic, the Godox is SO much more bang for your buck for event photography. Here is why it works:
* Li-ion battery: It lasts for like 480 full-power shots. No more fumbling with AAs in the dark!!
* Perfect Integration: It handles TTL and HSS flawlessly with the 90D system.
* Light Quality: The round head creates a much softer fall-off for portraits. I've used both, and I honestly dont reach for my Canon Speedlites anymore. The Godox system is just more flexible. Anyway, gl with the gear! 👍

For your situation, I’d grab the Godox TT685II-C for Canon. Honestly, I had issues with the pricey Canon Speedlite 430EX III-RT feeling underpowered at weddings... so disappointing. The TT685II-C is basically the same performance for like $130. * Full TTL and HSS
* Great AF assist beam
* Solid build It’s way more budget-friendly and works perfectly with the 90D. Plus, you can buy two and still be under budget, right? gl!

In my experience, indoor events are SO tough without good light. I was super worried about compatibility too, but: • Just go with Godox. I think you honestly can't go wrong with their Canon stuff.
• Be careful with batteries! I would suggest getting something with a rechargeable pack cuz AAs die fast... at least that's what happened to me. Seriously, third-party is the MOVE for your budget!

Regarding what #4 said about "Facts."

• Godox really has become the standard for 90D users who dont want to pay the Canon tax. The Canon Speedlite 430EX III-RT is a reliable piece of gear, but you are essentially paying a premium for the brand name. If you want the Li-ion battery performance without the round head price of the V1, the Godox V860III-C for Canon is a solid alternative. It fits well within your budget and offers several advantages:
• Fast recycle times thanks to the rechargeable battery pack
• A modeling light which helps with focusing in dark venues
• A dedicated physical switch to jump between TTL and manual I find that the build quality on the Canon is slightly more robust, but the actual light output and HSS functionality are basically identical for indoor events. It really comes down to whether you prioritize the brand reliability of Canon or the value and ecosystem of Godox. Tbh the Godox system is much more versatile if you ever plan to add more lights later... it just works.

Facts.