GnuTLS is LGPL and can be used alongside commercial applications. There's also Botan (BSD, C++), Bouncy Castle (MIT, Java).

Who should care if GPL is bad for a SSL library? First of all it needs to be correct and PolarSSL is the only one in this field. It is trusted, and it is fast enough.

I would never trust GnuTLS, NSS or OpenSSL over PolarSSL.