Hi Moni.
I use a .35 & a .4 this is for Vallejo Acrylics. Seems that most use these sizes from the writings on here.
Best with a tank as you get a much smoother air flow. Best 3l tank up.
Think if you look Moni you will find that a tank is probably only £10 to £15 more on the total cost.
Most of the less expensive ones are from China. I have had three two failures, one under guarantee, but there are many who have had no problems at all.
Beware as there are some models out there which are the runner of the mill as above badged up & smartened up externally at a great deal more in cost.
Some are noisy about 50 decibels or more. B & Q in the UK do a noise matt for washing machines & this has eliminated a lot of the thumping these machines make.
Make sure the tank has a drain which should be emptied periodically. Also a gauge, most do, & a water trap, most do. Do make sure they are specified for
airbrush work as some produced for other work spit oil.
If you wanted a quiet one, about 30 decibels, then they are about twice the cost. They have refrigerator type compressor.
If you are buying an air brush these are my thoughts. The best Harder & Steinback & Iwata. I started with the Evolution which is a superb item. Recently I got an Iwata Eclipse HP-BS which I have used about half a dozen times. This is a little honey. Literally smaller than most it is lovely to hold. I have had superb results both at distance of 150mm & very close it is very versatile. It produces better paint work than my H & S's & the Iwata Eclipse HP-CS. I did a comparison a couple of months back which is in the
airbrush section somewhere.
You can get cheaper airbrushes. But from bitter experience I have found the results are in proportion to the money spent.
Come back if you need further advice.
Laurie