I like the looks of windows with brick mold much better. I would stick with the 3 1/4. Without the brick mold, the windows just look like they are unfinished.

Is there an actual benefit to brick mold other than an aesthetic preference? I actually prefer less bulk, a more modern finish so thinner is better. But I want to know if it's something necessary.

Showing an image or two of the house and windows, and what windows you are considering will probably get you the best response.

Brick mould looks great on brick houses, not on wood houses, modern houses, adobe houses…

Black window frame is the 4 1/2 depth, no brick mold frame, white are my current old windows, and charcoal frame against wood are 3 1/4 depth with brick mold

For context, here is the whole house exterior.

I would opt for the one with the most glass, just based on aesthetics. Skipping the grids?

Thank you, that's what I was thinking...no brick mold = more glass. Definitely no grids! However, is there an installation benefit to brick mold?