When talking about context windows I'm surprised no one mentions https://poe.com/.
Switched over from ChatGPT about a year ago, and it's amazing. Can use all models and the full context window of them, for the same price as a ChatGPT subscription.
Poe.com goes straight to login page, doesn't want to divulge ANY information to me before I sign up. No About Us or Product description or Pricing - nothing. Strange behavior. But seeing it more and more with modern web sites.