Well, just look at the numbers. Research Coordinators aren't worth their price until you already have something worth making a 25% bonus for. So, if you only have two or three research facilities, then it's not worth it. That seems obvious.

As to power plants, I usually only put them on planets that have lots of factories, and in the beginning only on one that has my manufacturing capital. What's 10% worth if you only have 4 factories? It's not worth another factory. It's pretty simple to understand. However, when it's upgraded, it goes up. I don't remember right now how it works, but I think Antimatter goes to 15%, quantum to 25%. But those take a long time to get.

But NEVER destroy them, because once you do, you can't build them again. At least that's how it has worked in the last build I've played.

Both can be very powerful, though, so they're certainly worth building and upgrading on any planet you're serious about using for manufacture or research.

The anti-matter power plant is 20%, the quantum power plant is 30%. The bonuses aren't free, but half price like all other bonus production.

If money is a problem, then building these before building ANOTHER tile for a building you can't afford can work, but that situation is rare.

Hope that helps.