There is of course a huge difference between the two. Both seem to be of vinyl construction with the Champion being the more solid. My question is about the Low E/Argon Gas, is that really efficient as it gets or do the windows at Champion exceed that energy efficiency? Thanks in advance for all comments.
Yes absolutely, windows are woefully inefficient so Low-E, Argon, Triple-Panes (instead of the now standard Double-Panes) or ANYTHING that helps is paying you back sooner and a wiser investment. However, you must get both the R-VALUE (more so the glass area's insulation, higher is better) and both U-FACTOR and SOLAR HEAT COEFFICIENT (the entire window unit's insulation, lower is better) for the specific models you're considering.
Then, the Longer Warranty is any tie-breaker, as this indicates the sealing of the Argon inside is better or more reliable and long-lived. Don't let marketing and price fool you. For example, CertainTeed had an excellent window by all accounts for over a decade (the Bryn Mawr II model) that beat even most new windows (including CertainTeed's own newer models) of the time, but it only cost $200 (without installation) for a decent range of normal window sizes.