21 wroteYeah, GPU upgrade is definitely the first place to start. Would need to know what monitor(s) you're running(or are going to be running) to be able to properly recommend a GPU though.
If you're also looking to do monitor upgrade now, what is your monitor budget and any preferences you have?
CPU upgrade could be a decent shout, but honestly, your R5 1600 might still be fine for you? If you feel it's starting to hold you back, or you just want to upgrade then an R5 3600 would be a pretty reasonable upgrade, but I would probably be looking at an R7 3700x.
As for motherboard, your B350 Strix should support Zen2 CPU's so you don't necessarily need a new motherboard. That said, 1st gen Ryzen boards were pretty meh anyway, so an upgrade wouldn't be a terrible idea. Entirely up to you if you'd rather save the money an re-use your B350 board, or just upgrade it.
Aside from that, add 16GB RAM and a nice big NVMe SSD(1TB Sabrent Rocket Q is most likely what I'd recommend right now).
You could also take this upgrade as an opportunity to grab yourself an aftermarket cooler if you want. For cooler, I'd personally be getting a Be Quiet! Dark Rock (Pro) 4. If you're wanting an AIO, get whatever 240/280mm AIO you like the look of best- they're the same for the most part anyway.
This is great information, I am looking to further improve my setup and you've provided a wealth of knowledge for me to improve my streaming!