Question about lvl 70 Instances

My main question is what do you think is the easiest lvl 70 5 man instance?

I've got a group of friends now at lvl 70 and we need to gear up. We have limited playing time so I don't want to end up not accomplishing something because we don't have the gear for it yet.

I'm looking for oppinions on which lvl 70 instances are a good starting place and which ones are the harder 70 5 mans.

Thanks