I sold Semco for a hot second. I was very disappointed. No matter the cost I would not recommend. Pella is an average window, they still use roll formed cladding on their sash which is not as good quality as the extrusions their competitors use, but based on what I've seen might be a better choice than Semco if you HAVE to choose between those 2. Andersen 400 is vinyl clad so it's almost not in the same family of windows, but Andersen does honor their warranties well and seem to have few issues.

Agree with F_T 110%.