I have the Elecks 2500mW
I wanted to know of the most used the best power for the various materials:
The best power is for you to experiment.
What "looks" best is a matter of opinion. You should take a piece of each material you listed and experiement.
Thermoplastics (PLA and ABS) do not work well, you can engrave them but they don't hold much detail as they melt. Acrylic is excellent.
I always start with full power and feed rate of say 1500, if it burns too much you increase the feed rate and if it doesn't burn/cut you decrease the feed rate. If you end up at over 3000 for feed then it's time to start reducing the power.
Technically you should be able to engrave at speeds higher than 3000, probably up to 4000 but your machine needs to be perfectly setup with low friction and belt tension. I usually suggest 2500 max as a safe level for good results.