Silverline has not been owned by Andersen now in several years. They are now owned by Plygems as Andersen basically replaced the Silverline line with their 100 series as its entry line builder grade product. Silverline is pretty much bottom of the barrel as far as quality goes. What other lines will your builder consider? What type of window (casement, double hung, etc.)? Patio or Hinged Patio doors? Any idea on budget?

"I have seen several threads mention soft lite and Okna but these are not easy to find many reviews on."

There are plenty of reviews here, all good by the way but they are typically sold only thru their dealer network and not available to a builder.

We have a meeting with the builder today to discuss architectural plans for the home. We have not gone in depth regarding the windows as of yet. I am guessing the initial paperwork we looked through that mention Silverline windows as part of Anderson was an outdated spec.
To my knowledge there are no limitations on what we can purchase as they are custom builders however we would like to keep the project cost efficient where we can.
It’s hard for me to gauge budget as I don’t know how much of a differential there would be between the silver line and a higher in product like the soft lite and Okna but any advice or direction pointing would be greatly appreciated.

Are there any lines within Anderson or Pella that are decent?

Some folks are higher on the Andersen 100 fibrex window line than others. Not widely loved nor hated. I would't recommend Silverline nor any vinyl from Pella. The aforementioned Okna is located right in your PA back yard, and they are pretty much the gold standard in vinyl and composite if that is what you are after. I'd highly recommend checking further into that option. Softlite is also good as is Sunrise and some others.

Will certainly start looking into the Okna line and soft lite. Are there any particular lines within Okna or soft lite companies that are considered “best values”?

As far a builder will go...he will most prefer the Okna Insult-Tec because of its availability with an integral nailing flange. Builders don't want to mess with a clip in flange.

+1 on the Insultec 500/5500. Not a ton of bells and whistles, but still a great performer and its set up with the nail fin for new constrcution installation.