There are no 'best settings', as everyone's setup and situation changes radically with a TON of different variables.
A good way to get 'baseline' settings is to go to the Tools menu at the top of the OBS window, and choose 'Auto-Configuration Wizard'. It'll test your hardware and connection speed, and generally give you a good starting point to work from.
I will say that your CPU and GPU are both somewhat on the weaker end, but it doesn't look like your test streams went too poorly, with only small amounts of render delay and encoding lag.
Two immediate bits though:
1. If you are recording locally, NEVER record directly to mp4
for any reason. It's not a 'safe' recording format, and is VERY easy to have a minor hiccup and end up with a corrupted, absolutely un-recoverable pile of digital garbage that you have to delete and then re-record from scratch. Record to MKV instead, and use the 'Remux Recordings' option in OBS' File menu if you need mp4s for editing. You can also set it up to auto-remux completed recordings in the Settings->Advanced section, under the 'recording' heading there. As an added bonus, editors like Premiere, Vegas and Resolve tend to have problems with mp4s natively recorded by OBS, but have no issue with remuxed mp4s.
2. Speedtest.net and similar are worthless for livestreamers. They test peak throughput speed, not minimum constant throughput speed (which livestreaming relies on). If you're streaming to Twitch (and it appears that you are), download
R1ch's Twitch Bandwidth Tester. You want a server with a Quality score of at least 80, preferring 100. This tool tests your actual connection to the Twitch server, and provides streamer-relevant speed and quality results. :)
