What is better English?

'We'd love to see you joining us as a helper!'

or

'We'd love to see you join us as a helper!'

What is the rule?

What is better English?

'We'd love to see you joining us as a helper!'

or

'We'd love to see you join us as a helper!'

What is the rule?

Edit: Also, after Joe's comment, I should add that I'd like to have at least some formal side to this (meaning, that joining is something that has to be announced formally).