Should I use a spray machine or brush to paint my kitchen cabinets?

I do not know since the they were taken back to the shop to be done. They did spray the outsides of the cabinets. They made a plastic tent in the kitchen and covered the front interiors as well so I did not have to empty the cabinets. There are no brush marks but if it is oak the grain may show. I do not she any grain on the doors, some on the sides but you have to look closely.

Remove the doors and hardware. Mark the doors and cabinets with tape where they go. Lightly sand the doors and cabinets to remove any gloss and roughen the surface for paint. Prime with a stain blocking primer like Zinsser 123. Then paint with your color. Seal with at least three coats with a water based polyurethane. Use a small foam roller and foam brush for a smooth finish.

A foam brush will leave a smooth finish. If you want brush strokes so it looks like wood grain, use a foam roller for coverage then go over lightly with a brush for a natural wood look

if you don't want brush strokes to show then I'd spray with a sprayer.

Pros always spray the cabinets so they don't have the DIY look that painted cabinets often have when painted with rollers and/or brushes. Using a sprayer takes a bit of practice on some old plywood pieces to get the technique downpat before tackling your cabinets that are seen everyday.