There is no such thing as a "best airbrush" out there.
They are like any other tool in which there are several well-made ones that produce similar results.
Paasche makes a fine airbrush as does Badger, Iwata, Sata, Harder & Steenbeck, etc.
I have seen excellent work from every brand and single and double-action alike.
My recommendation is to buy the one that feels the best to you and then practice, practice, practice.
You don't learn to play the guitar like Stevie Ray Vaughan in a couple of weeks and neither will you master the airbrush in a short time.
It takes practice and patience and you will begin to see results fairly quickly once you train that finger to work together with your brain.
All of us started out like you and many of us have learned to use them well regardless of the brand.
I hope this helps.
Mike
“Wisdom is the right use of knowledge. To know is not
to be wise. Many men know a great deal, and are all the greater fools
for it. There is no fool so great a fool as a knowing fool. But to know
how to use knowledge is to have wisdom. " Charles Spurgeon