Bill,
I have both, and for overall painting I like the Anthem better. More versatile for me at least. Of course if you paint large subjects like 1/35 armor and small detail is not as important the 175 would do the job as well.
They are both very good brushes but at least for me the 155 had less of a learning curve to it. I know this might be confusing mut it's the best I can do. You might ask to hold them in the store as both have a very different footprint as well. The 175 is a fat stubby little guy and the Anthem is slender. find out which ones FEELS better in your hand... I thought I would like the 175 better when I bought it but ends up I prefer the control I feel when I use the 155.
I also had an Aztek before the 175 and 155 and MAN what a difference for me!!!
---edit---
I just noticed your sig pic and I am assuming you do armor like I mentioned, just wanted to let you know the 155 does very well on large subjects too, I guess MY preference would be the 155, was just trying to give you both sides of the info haha It just boiled down the the 175 was a little too awkward to hold close in to the model for me as it is kind of a big brush...