Stand Alone - I actually went and brought another license (different account on forums that's why no badge) so that I can use standalone. I had endless issues with steam version (nothing to do with construct2 but rather steams authentication system that caused periodic crashes amoungst a whole list of issues.
I still use my steam version to open example capx as steam version has all 3rd party plugins and that license is tied to this forum account. I will note it has improved since back then. But seriously, I would go standalone without a doubt, especially if the price difference is only $12.