Which is correct? When to use present simple and when present continuous. When I recommend / recommending something someone on StackExchange, which tense would be better and why?
Both are correct
The present shows that you recommend something, and you may do it multiple times:
I recommend this to my customers.
I recommend that you use this.
The present continuous suggests that you recommend something at the time of speaking:
I am recommending this to my customers.
I'm recommending that you use this.
Both of these show that you are actively recommending something right now instead of in general.