It usually comes down to: what can I learn tonight?
I mean, usually you can put a meetup talk in one of these three buckets:
The vanity talks are usually nothing more than what you could learn by doing some homeworks: watching some conference recordings, reading some whitepapers... So if you don't have time to do this, and prefer to catch-up later locally with free pizza, then these kinds of talks are nice. If you're quite up-to-date on the subject, then the free pizza is the only thing worth.
All that to say, that all the best meetups I had were when there were a real story about what were the good, and the bad part of adopting/changing this or that. No matter if it's developpement oriented, infrastructure oriented or whatever. Knowing the good parts is easy, usually that's what has the most visibility, so it's easy to learn about it even without meetup.
But meetup are the opportunity to meet and listen to people who tried this before you and hopefully did well, but - as any tech change - faced issues, unexpected problems, and had to solve them. When the present these challenges and how they solved them, that's usually a great meetup, where I learn something I couldn't easily learn on my own, until I face the same issues.