Hey Segler!
Great to hear from you. I hope you're doing well. It's been... 10+ years?
This is a perpetual question: https://forum.il2sturmovik.com/topic/81398-sorry-for-the-newb-question-steam-vs-stand-alone/
In the past, I think it mattered, as Steam was updated more slowly.
However, nowadays, I don't think it matters as much. They're interchangeable in terms of server access, etc. So you're not missing anything by going one or the other.
However, once you're on Steam, you're stuck on Steam. And once you're standalone, you're standalone. You can't mix or match.
Others might have other thoughts.
Not sure if that helps!