Since I'm going to be in the same position soon, my view is that there are so many spells competing for the two Magical Secrets positions that it's always a tough choice. Misty Step is a very viable option. It's usefulness is however, as mellored states, situational. Is the 'get out of danger' spell going to be useful enough for it to be chosen over some other spell? Only you can decide that.
Personally, for my 6th level Magical Secrets, I'm looking at one spell for support and one spell for defense. I'd love to also have one spell for attack, but I only get to choose two....