It doesn't matter whether you use if or try_files. If people would actually read the if is evil page then it specifically states that "It is important to note that the behaviour of if is not inconsistent, given two identical requests it will not randomly fail on one and work on the other, with proper testing and understanding ifs can be used."

If you prefer if then use an if, if you prefer try_files then use a try_files, there's really no reason to agonize over this issue.