I'm not sure how the entire instance is but I follow @[email protected] from there so they can't be all that bad! Jokes aside, (though you should really check out FoxNews the #1 fox news network on Mastodon), mastodon.art is very cool and has great vibes. Where ever you end up signing up, I encourage you to find some people from .art and give them a follow to inject your timeline with the good stuff.
Tech.lgbt is a tech focused instance for people with marginalized identities. I follow a few cool peeps from that instance.
peoplemaking.games is an instance for people who work on games, whoduvthunkit. Peeps from there seem cool when they come across my feed.
That all being said with mastodon it's more important that you vibe with the admin policy than the subjects focused on by the instances. I am on .art, but I also am into urbanist stuff and bicycling (especially as a mode of transportation, not as a sport), so following hashtags like #biketooter puts that kind of stuff in my feed. My advice is to take the suggestions you get from this thread, and maybe look at a few more from your own searches, and check out the instances patreon to see how well they are doing, what kind of news updates are they posting (notes about defederating from bigots is a pretty good start there), and then choose a small to medium sized instance that seems like it will stick around for a while. Then go ahead and follow whatever topics you want.
