I would do satin IMO semigloss is just too shiny and shows every little imperfection

I seldom use anything shinier than eggshell on walls.

Are you thinking you may need to wash any of the walls?..if so satin would be better

I think concrete walls will always look better with flat paint

Not in a basement flat paint will never look better. Basements are dirty dusty places. Flat paint will soak all that dirt and grime up like a sponge. And then if you happen to brush against that dirty wall, you'll have to go get a change of clothes because all that grime rubs off on your clean clothes.

Kelly ...is your basement dirty and dusty?

Um... not all basements are dirty and dusty.

Matte paint is beautiful but tricky. Benjamin Moore is SO flat, it's like chalk. so easily marked. I can't even clean it with a cloth without accidentally burnishing it. Never. Again.

I have better luck with Behr Ultra. Their flat is more like a flat/satin hybrid. I've used it in several rooms now. Our basment was painted with Pewter Mug in flat, and even 2.5 years later, I still love it. would 100% recommend.