Choosing the best string methods for your needs is as easy as identifying which ones are relevant to you. There's no one-size-fits-all option here, because there are plenty of different steps to take while learning strings, and each book is designed to help you on one of those steps. That said, if you're just starting out, there are a few that you should check out first and foremost. The Hal Leonard Essential Elements for Strings series is one example, offering tailor-made methods for all strings including the violin, viola and double bass. For a well-rounded approach, you can partner these up with supplements like the Alfred I Can Read Music for Violin, Volume 1 Book, designed to walk you through reading sheet music written for your instrument.
Those beginner guides are only the beginning of what you'll find in this section, a variety that also includes advanced materials and even instructional aids such as the Hal Leonard Essential Elements 2000 for Strings - Teacher Resource Kit. So it doesn't matter if you're the student or the instructor; there's something here for you. The only question you need to ask is which things those are specifically, and the best way to find the answer is simple: start looking!