With witnesses, it can take a while to get to know what each one stands for or contributes, so don't worry too much about getting votes in at this stage in your journey. You shouldn't necessarily vote for this in the top 20 either, because things just become static then. Don't want complacency when there are issues that need addressing. 😉 I do still have votes in for quochuy and ausbitbank, but know them fairly well and that they stand for the freedom of censorship on the blockchain. They've also done a lot to help support users and to code things.
Aggroed is splinterlands, so some amazing work from him. Mahdiyari built Hive.voter and has always strived to provide it for free. I see someguy123 has popped up into the top 20 now. All I know about that one is praise from other users about how they've had so much help when they've needed to retrieve a hacked account, so that's good enough for me. Arcange does a lot to raise awareness of scams and safety, as well as what's on the witness profile. Steempeak is peakd, as you probably know... I'll stop there because this could really be a post and I still don't really know enough about enough witnesses.
You can also delegate you vote to someone you feel has a better understanding and a similar ethos to yourself.