There is so much stuff on YouTube that it is possible to find practically anything.

So, instead of suggesting that you cover a specific topic(s), I suggest that you cover any topic that you are passionate about, and well-informed enough to present in articulate, well-documented ways.

When you do select a topic, you should Google it and use the YouTube search function, before you make a video, to be sure that there isn't a lot out there that is easily find-able and already says what you want to say.

But the most important thing is for the subject to be something that you are interested enough in to dig deeply into, so that you can be sure that you are saying things that are enlightening to viewers, that they have not seen/heard before.

I have a YouTube channel. It is no exaggeration to say that I spend 5-10 hours researching, producing, etc., for every minute of video, sometimes more.

Here's my channel (You will have to cut-and-paste the link. That's the only way I could get it to work):

www.youtube.com/user/freethinkersbooks

The range of topics they cover are great, and a good source of entertainment. However I do feel that many do inadvertently "feed the trolls".

There are some out there "Militant Atheists" that do seem to be merely the other side of the coin so I'd bare that in mind.

I often find it fun to point out that all religions are just a part of the same whole. Basically, all the titles, words, etc... that humans have given for their chosen god/s are simply that. Human created words to describe what they can/do not know; akin to 'god of the gaps' in a sense.

For instance, a person who gets all in a huff for saying "god damnit" yet doesn't mind if you prefer to use "allah damnit" is a theological hypocrite of the lowest degree. Have fun with that!