Is airbrushing better than hand painting?

Both methods have their pros and cons.

It takes a little practice to get proficient in using an airbrush but once mastered is a great way of painting especially for large areas, weathering and varnishing, with time and technique there is very little that you cannot achieve with an airbrush apart from very fine detailing.

You will always need a good selection of paint brushes.

There are some very good tutorials online showing how to airbrush and hand paint. These are well worth watching even for the more seasoned modeller as there seem to be different techniques from many modellers appearing all the time.

If you do not yet have an airbrush it is definitely worth having, and once you start using it you will wonder why it has taken you so long to get one.

There will always be a need for paint brushes as some brushing techniques cannot be replicated by airbrushing.