I've always had a strong dislike for Theodora/Thea but I can't put my finger on why. On the other hand, I love Isla despite its popularity. I really like Skye and think it works perfectly as both a middle name and a first name. Not keen on Evangeline, too fussy.
I like Isla Skye, but that can't be used for obvious reasons 
I can't really pick between them. I'd say Theodora Skye flows slightly better than Isla Evangeline, but overall I prefer Isla as a first name.