I use B at home. At work, I use what ever is currently in place or what is dictated (federally funded jobs require A).
The need for a crossover cable is getting more and more rare everyday due to auto negotiating NICs. There are some cases where I still need one (using an old Dell 500 series laptop running XP to access an old piece of equipment for example). But even then, If I can get the software to run in a VM on a new machine, then the new NIC will auto negotiate and make it work. An exception, on some equipment that I've worked on, the RJ45 port isn't a NIC but rather a serial port. In that case, a crossover cable might be required depending upon how the port is wired internally. RTM for that.