I haven't stained or varnished much but latex glosses all suffer from brush marks to at least some degree ime. There's internet wisdom which recommends adding extenders such as antifreeze but I never wanted to roll those dice.
The last bunch of flush panel doors (doorway doors, not cabinet doors), I just used a 4mm nap microfibre/mohair roller, rolled pretty dry. 
Slight, uniform orange peel beats brush marks, hands down. Might try a foam roller at some point and see if it's any flatter. Everyone was happy but I felt I could do better. It was pretty much the finish I'd get from an airless but I want a fucking mirror. In water based, guess that's the grail.
Think I'm going to buy a Kremlin air assisted airless. I always spray trim so want production quantity rather than a pot gun. Critics say AAA solves a problem which doesn't exist since all you have to do is water down the paint to get it to gel and eliminate spray fingers, but I'm not interested in watering down the paint. I'm willing to heat it to reduce viscosity but I don't want to fuck with the formulation. The bond would be fine but it kills the thixotropy and hang, so now you're shooting for lesser coverage to avoid runs and doing another full circuit around. Also, every pro painter I've spoken to who poo-poos AAA has never used one and is rough as a badger's ass. Doesn't mean they're wrong but pretty sure I'm going to ignore them since my work is miles better than theirs and I'm not even a 'real painter.'
Did you spend any time with AAA or HVLP in your days, Prime?
I did not and have not ever used an Airless, AAA or HVLP. 'My day' was a long time ago.
When I worked with my dad, who was a painting contractor, I did all the brush work. Cutting in walls and ceilings was a snap and a workout because you're up and down the ladder a lot. I also did the trim, using oil based enamel which was pretty much the only choice back then. I could knock out a divided light window pretty quickly. When my dad started in the business, everyone used brushes because there was no such thing as rollers.
After moving to Portland, I worked with a painting contractor who only did high-end work, mostly for repeat customers. The only area he rolled was flat paint on walls. In rooms where some sheen was called for, like bathrooms and kitchens we brushed the walls using oil based enamel for a super smooth finish. All trim work was done in oil and brushed. There were no visible brush marks.
One of his customer's home was painted with lead in oil on the exterior. Al bought up all he could find when it was being phased out just for this client. The method of application was to brush it on two or three siding boards at a time and go all the way from one end to the other so there would be no overlaps. Damn that stuff was heavy. After 8 hours of bushing it on with a 5" brush, my arms were pretty sore.
Only recently, did I begin using water-based enamels. My preference is semi-gloss or velvet type finishes. If you really load the brush, tapping the paint in and brush a section without lifting the brush, it comes out pretty darn smooth. You should avoid going back over the area because the paint sets up really fast and you will get laps. Better to wait until the paint is fully set up and repaint the whole piece. -Always buy the highest quality brushes you can find.
Never heard about adding antifreeze. Seems like it defeats the whole purpose of using low VOC paints. Isn't antifreeze tinted with blue or pink? I think this might change to color of the paint ever so slightly.
