Okay, I have a room that has just been taped, floated, and is ready to be primed & painted. There is NO TRIM in this room yet as it was taken down to studs for the purpose of installing insulation in all walls (old house-long story).
So, imagine a completely bare room with fresh drywall that has been mudded, taped, floated, and is ready for priming & paint.

My personal thoughts; prime and paint all the walls now using a roller, and then paint all trim before cutting and installing it. This way, there is no taping and very minor touch up of the trim after it is installed. This is the way I have done all the other rooms in my house up to this point. In my opinion it's the fastest way, with the least mess, and the shortest amount of time. I can literally use a small sponge type roller and paint all the trim on sawhorses for an entire room in under 45 minutes and that includes priming, and 2 coats of semi-gloss trim paint.

My general contractors thoughts; Install all floor molding, door casings, crown molding, and other trim, and then paint the trim after it is installed, then tape everything off, and then prime & paint the walls.

My G/C wants $1800 to do it his way.. I'm thinking I tell him his time is finished and he can move on to the next job and I'll do it my way. I have painted every room in this house up to this point but have now decided to let my G/C handle finishing the kitchen.

Not discussing the money aspect, which way would you guys think is the better way?

As a trim guy and painter this is what we do....After tape bed and texture I trim the whole house....Next we will spackle all holes and sand after it is dried ..Then spray oil primer on all wood...Sand all wood along with caulking all trim into walls.....Spray two coats oil paint....Sprayed trim will always look better than rolled or brushed but not everyone has a sprayer..Then roll ceilings and walls with primer..Then two coats paint cutting in edges as we go...

For a DYI bedroom, breakfast area, home office etc, Roll and brush as you descibed.No over spray to deal with in rest of home. This would probably be my choice. Use paint conditioner, high end brushes and high end paint.

For a formal area, or if time is important....contractor method.

Desired results and time line would determining factors.

Do it the way you are saying. I would prime and put first coat of wall paint. Prime & paint trim on sawhorses (I prime all sides) then install trim, caulk to walls. put final coat of paint on walls and touch up trim.

Doesn't mean either way is wrong, thats just how I would do it. I was a paint & wallcovering foreman for 15 years and have been a paint & wallcovering Estimator (commercial) for 13 years.