What paint sheen?

Geez,I have no idea.Why don't you ask the wife or maybe you mother.

Match the finish to other mouldings in the room like door trim, base boards, etc. I like semi gloss latex wall paint as opposed to enamel. Much easier to apply. FWIW

Dont see why this has to be asked....its your house, paint it whatever finish you want to. We dont have to look at it.

I think he's asking which finish will render the best sonic advantage.
I have no clue. But I can't believe no one here has an opinion.

If you had unlimited finances finish the columns with Anti Vibrational Magic {AVM} it works. Next would be a spray stone paint finish available at the Depot or Lowes. If the columns you have now are of the right angle type remove them and replace with the following. The rough stone finish on a tapered or sculptured column will have random harmonics travel along its irregular surface versus those of a smooth finish on a perfectly symmetrical column which may generate a more singular resonance or peak. Tom

I'd use flat. It won't reflect the light from the TV and create a glare. Several manufacturers sell a "ceramic" or likewise flat paint that is washable/durable, unlike most flat wall paint. A multi-color textured paint such as Multi-spec or Poly-mix would give the columns more of a natural stone appearance and have a flat finish as well. Most of the multi-color coatings must be spray applied, however.

i was asking for light reflective reason, thx mouse

Eggshell holds up real well. I will tell you that Sherwin-Williams is the best paint I have ever used. It costs more but if you plan to stay there and don't really enjoy painting. Pick a good color and get SWP. I have had many good experiences on warranty and coverage issues. And I have noticed tighter bass and reduced shrill in the highs.
Or maybe that was the amplifier....hmmm. Oh yes now I remember!....It was the color I picked was so ugly I closed my eyes and listened more intently.

I'd not get to glossy with the pait choice. depends on where the colums are placed. Perhaps doing the tops and bottoms of the pillars in a gloss and egg shell (least glossy.. just above flat or matte) on the uprights themselves.

It might prove a good idea to take this opportunity to add some 'life' into the room, or carry the theme out as is.

Re-reading your post I don't think it too critical for or against the on screen image visualization. I'd be more concerned about any distractions like those from ambient glare of the screen's light upon the pillars to either side of the screen more than anything. That could well be an issue for me. I'd prefer non reflective paint there... and what color depends again, on your theme and just how much attention you want them colums to get.

I think I would go with either satin or eggshell rather than using the glossy. Between those two I do not think it will matter all that much.