I get asked a lot, "What should we wear to our engagement photos?" And the answer is simple! I always recommend wearing something that feels like you! I had a groom to be who always wore flannel shirts so his fiance made sure he wore his favorite flannel to their engagement photos!
Recommendations
Make sure your outfits do not clash. For example, if one of you is wearing flannel or plaid and the other is wearing bright purple polka dots that might not be a great pairing!
Stick to a theme. For example: both wear neutrals. Maybe even one person wearing a solid and the other adding in some pattern or texture like the image above on the right.
Are you both bold people? Wear something bright and bold!
Comic fan? Marvel fan? Wear something that goes with that!
Another thing I recommend is doing one outfit that is more casual and one that is more dressy. This way you have some options when you go to choose your images for your save the dates!