hand brush is suitable for Matt finish color, & weathering kit.
but not good in Car model, & aircraft.
AB (airbrush) is better, faster & good for matt & gloss finish.
AB set nowaday is quite cheap + reliable, small size & low noise. price range below rm 250 for whole set (AB + compressor).

for airplane u better get AB.

Brush paint AFV still ok, all my build posted here are brush painted.

But aircraft better go to airbrushing, coz aircraft surface much smoother, which is hard to create by brush.