Even where the GPL is fine, LZO consists of some pretty scary code. Though at this point, I think probably enough people smarter than me have understood it and deemed it safe (it's part of the Linux kernel).

Snappy is fine as long as you can use compile C++ and link against the C++ standard library as it uses std::string for byte buffers for some strange reason. I can only assume it's mainly used for compressing strings at Google, but unless someone ports it to C or at least rips out the standard library dependency, that will preclude its use from some embedded systems, or the Linux kernel.

As a substitute for LZO or Snappy, I recently integrated the BSD-licensed LZ4 [1] into a project where no C++ standard library was available. Dependencies are minimal, memory use is predictable and the code is actually readable. Speed and ratios are comparable to LZO and Snappy.

[1] http://code.google.com/p/lz4/