For video you rent from Netflix, Prime, etc, get another box. The 103 has some of those built in that I've never used. The 203 doesn't even have them.
For audio-only streaming, get another box.
The OPPO excels at playing media you own that is video-related. For videophiles the OPPO also has a bunch of features that are a tweaker's delight and are apparently very helpful for projectors. For transcoding video during playback from DVD->2160p, BD->2160p, 2160p->720p it's hard to beat.
As I've said before, if all you want to do is put a disc in and play it, go to Costco and get the cheapest UHD player you can find. They're all the same in that respect. It's the other features the OPPO has that no other player has. I've even used it as a pre-pro. See here for what it can do:
https://www.avsforum.com/threads/official-oppo-udp-203-owners-thread.2676801/
It's funny you have no experience with the OPPO and yet come across a bit belligerent about it's lack of capability. Maybe I'm misreading your tone?