PuTTY is a testament to compact application building. It is the SSH client that can do anything you need it to. It can recognize the most obscure keystrokes that not even GNOME terminals can pick up on.
All other Windows SSH clients shadow in comparison to PuTTY. There are zillions of features packed into PuTTY and it still manages to keep the UI minimal, aside competing SSH clients that tend to bloat the interface.
PuTTY's always been there when I needed it. I still use it even after several years of use.