You should have mentioned that some tools are true synthesis tools, while some of these are really "parametric blocks" e.g. the tools from Matlab and Synopsys Module compiler, Synplify DSP are not true synthesis engines. There is behind the scenes structures which are modified via parameters.
Other tools e.g. Catapult, C2S, Forte, AutoESL, are true synthesis engines, where you can create arbitrary hardware from an input description + synthesis directives.
Also, you should have mentioned that Catapult is the dominant C Synthesis tool for many years in a row. Mentor was an early maker of High level Synethsis tools, not late to the market (they just didn't have an RTL synthesis tool other than the ones aquired from Silicon Compilers)