Mostly, I prefer to show them in fighter mode, I have trouble keeping some of the VFs balanced in battroid mode with all their Fast Packs on.
(The YF-21 is notoriously difficult to balance even without its gun pods attached!)
The Yamato VF-11 is perhaps the only gerwalk mode I actually find cool. The lines on that bird are so clean, and its weighted just right, It's a joy to pose!