For what it's worth, in case anyone's interested
in quality interior trim painting, this is about getting
an elegant, oil-base paint look. (If you don't see any
difference between acrylic and oil paints on trim then
this won't be of interest.)

I was looking for advice recently about best
options for interior trim painting. I used to use Benjamin
Moore Satin Impervo oil, which has been reformulated
twice and is now junk, despite having the exact same
label on all 3 formulations. (Satin Impervo #235 was
wonderful paint that dried to a glass-like finish. #C235
is reformulated and looks no better than acrylic paint.
#Z235 is reformulated again. It goes on like oil-base
stain, with lots of spattering and obvious brush marks.
I also had trouble with it peeling off of radiators.)

To replace Satin Impervo I
found Pratt and Lambert Red Seal oil-base satin finish,
which gives a beautiful, smooth finish with virtually no
brushmarks. It's a bit tricky to use, requiring periodic
thinning, but otherwise is as good as anything from
30 years ago. Unfortunately, P&L seems to be getting
withdrawn from the market. Even their own salespeople
couldn't tell me a store where it's still sold in my area.
Their list of dealers was years out of date! Sherwin
Williams bought them out some years ago and seem to
be deliberately killing the company.

So, I've been doing some research. The best option
I can find is Benjamin Moore Fresh Start oil-base
primer and underbody, topped with Sherwin Williams
ProClassic acrylic/alkyd semi-gloss trim paint. Benj
Moore Advance is similar to ProClassic -- a "waterborne"
oil paint with water cleanup. But SW seems to be a bit
thicker and dries in 4+ hours, as opposed to 16 hours
for BM Advance. Both dry to a very smooth finish but
are thin, like glazes. That's why the underbody is needed --
to give the finish enough thickness to cover fine irregularities.
When I tried ProClassic on poplar, over a thin water-base
primer, I could actually see some of the poplar grain after
2 coats! (Poplar has *very* fine grain.)

Sherwin Williams has several primers I haven't tried,
but they don't even make an underbody paint as far as
I can figure.