I like the Hackett marked snap forend (the kind with the small roller at the end of the spring) on my Lang. Seems efficient and simple.

The Deeley style on my Greener FP was good with excellent fit, finish and function. Feel like there is more to go wrong there in the long run though.

Conversely, I feel a little bit of slop/play in my low mileage Citori with a Deeley style forend...I understand it can be an issue with the Berettas as well although my Silver Pigeon was tight if memory serves.