The 200NH and 155 Anthem share the same head. The difference is the 200 is single action and the 155 is dual action. Both have the "new style" head, which I have heard can have alignment problems.
If it were me I would go for the 150, 100G or 100LH or RH (left or right) side feed. The 150 is a siphon fed brush and can use bottles or color cups. The 100G is a gravity fed with a medium size cup. The 100LH/RH is side feed which only uses the color cup. They are all the same airbrush except for the paint delivery system.
If you do a lot of single color painting, then the siphon fed would be the better brush. If refilling the cup isn't that hard for you to do, then the 100G would be a better all purpose brush. The side feed version is somewhere between the two, sort of a gravity/siphon feed. Here's how I would rank them:
- 100G
- 150
- 100LH/RH
- 155
- 200NH
In reality the differences between those five airbrushes are very small. More like this list:
1a. 100G
1b. 150
1c. 100LH/RH
2a. 155
2b. 200NH
I spray only acrylics, and own the 150 and two 100LG (large cup) as well as the old style head 200-20 detail single action. It's too bad you missed out on the 100LG or Omni 4000 (I didn't, I bought both kinds!), as you would be hard pressed to find better brushes without spending twice the money, even at regular price!
Now I might be a bit biased towards the old style head assembly, as I have four airbrushes that use them, and can be interchanged between them. This keeps my spare parts supply to a minimum!