I feel obliated to stick up for CC series.
I enjoy CC3 and still play 1 of the many mods for it, plus CC3 has literally 100s of custom made maps. True the game has its limits, but it is still one of the best small scale wargames I have ever played. But once you get into playing CMBB you wont be playing much CC. CMBB is so much deeper that it will keep you from reaching for CC3. Try both, CC3 has a ton of custom mods/maps and now even user made campaigns and ops. CC3 is fun when you only have 45 minutes to kill and want a "Quick game".
But if you have to chose 1 or the other get CMBB.
You wont regret it.(especially if you are a grog)
the scope and scale of CMBB is mind boggling at times but truly awesome.