PuTTY is the best open-source terminal emulator out there. Unless you're having issues with it, there's probably no reason to change. That said, I have met several network engineers who much prefer SecureCRT. It's main feature is session/connection management; when you're making a change that needs you logged in to 15 devices at the same time, having a good tab management system is a big advantage.
There is a comparison of SSH clients on Wikipedia
I use SSH Secure Shell Client 3.2.9 because it has support for both ssh client and ftps client.
But.. I tend to come back to PuTTY.
I've found a new program just today through superuser.com and that is ZOC SSH/Telnet Client.
ZOC is like SecureCRT (also for $$) but available for Mac and Windows in very similar versions so I can use it on my Macbook and Windows Desktop with the same configuration and don't have to do thins differently.
In my opinion, one of the best SSH Windows clients is XShell 3.x. A few years I used Putty, and it's nice, but XShell is the best one!
I use SSH Secure Shell which is now called "SSH Tectia Client".
Note: It has a "sister" sftp product as well which I found useful.