There are two major fix engines:
What are cons and prons of each of them? I know that Fix Antenna is faster, but what else?
Is QuickFix project alive. Changelog shows that last commit to QuickFix was at 2010-04-06 06:22, does it mean that project is dead?
As DumbCoder says, there are a lot more than 2 major FIX engines. Cameron tends to be used by a number of investment banks. Rapid Addition also have a highly regarded FIX engine - and there are lots more. QuickFix is very popular and is relied on and used by lots of individuals and trading businesses and can be an excellent choice unless you are very latency sensitive.
There is always also the option to write your own. It depends on your use case. If you aren't hugely latency sensitive (care about microseconds), then QuickFix is probably your best bet. Otherwise, if you do care about every microsecond and want more predictable latency per message processed, then QuickFix will not work for you and you either want a low latency commerical solution (such as Rapid Addition Cheetah) or you want to write your own which is optimised to your usage scenario. Note that writing your own to beat the performance of a commercial solution will take some time and is no easy feat as many of the commercial engines are now highly performant.