64 bit all around. If you are taking the OSCP exam they recommend using their 32 bit OS but it can be done with 64. Really they both will do just fine for everyday use but if you use lots of RAM you have to go with 64... also if 32bit apps start to phase out and are replaced with 64 then the 32bit gang will get left out
Been using x64bit for almost 6 years, reason being when i bought my Laptop it came with a 32bit OS and i checked out my spec and my laptop was capable of running x64 bit so i did a clean install and chose x64.
Why PC/Laptop manufacturers dont check this first?
I stayed with 32-bit until last year. Finally stepped up to 64-bit with Windows 10 because my hardware was x64 capable. It did require a clean install from Windows 7 to upgrade the bit level, but was worth it. Was also a good opportunity to increase the RAM!
It seems that some developers are dropping support for 32-bit applications as they roll out new versions in 64-bit only. Having a 64-bit OS is win/win, because you can run both types of applications!