1) Wordpress: I can make a basic nice looking site and then outsource for more complex things....but I really dislike it. Customers always want more for free, so many bugs, stressful.

Well... which do you like more... doing WordPress coding or living out of your car.

I work with WordPress all day, every day.

The trick to keep from going insane is to build your entire business around continuity.

All my WordPress clients are setup on PayPal recurring subscriptions, so I do some work, then get paid forever.

2) Instagram: I have some experience with Instagram in posting photos on IG would be lots of work but fun work. And I get paid by the hour.
If I choose this I can go through some courses and know probably more than 80% of anyone else.

A likely prospect + I'm far to lazy to do this because, WordPress work tends to pay more + drives easily to continuity income.

3) Video editing: I have some experience using Adobe premiere pro, a little with doing actual filming. Again I could take a course to be good at is.

Super time intensive. No one's ever 100% satisfied. Lowest income/hour of the 3x you mention.

4) If you could start a new service, would you choose an IG marketing service or a video editing service to start?

I'd go for WordPress site work driving to continuity income.

5) PS- I there a way to check how well companies in these fields are doing?

Not really an issue.

Better to determine how much income/month you require, then look at markets, determine your price points, then get started.

There are many breathing humans alive right now, enough of which are interested in any of the options you mention... enough will buy to keep you from living in your car.