Most of my ADR work is with a 416, but really depends on what mic the A2 boomed with originally.

The U87 is a great mic, but it sounds out of place when you are trying to match loops with the pre-recorded stage sound.

Don't confuse ADR with voice-over and narration. The objectives are quite different. ADR attempts to duplicate the sound qualities of the original location (or what the audience believes would have been the location's sound qualities). It is part of the story, somewhat removed and distant from the viewer. VO and narration is more intimate, the speaker is talking directly to the viewer and is not part of the story space. Imagine you are in a theatre watching the film - ADR is dialog on the screen while VO is your friend sitting next to you commenting on the movie. For VO studio mics are the norm but for ADR mics that will give a similar 'feel' to dialog recorded on set are preferred.