In the English version of Final Fantasy X, Tidus is voiced by James Arnold Taylor. Taylor is known for voicing a variety of characters like Obi-Wan Kenobi in Star Wars: Clone Wars, Wooldoor Sockbat in Drawn Together, and Ratchet in the Ratchet and Clank series of games. Taylor stated in an interview that although he does voices for a living, Tidus has his actual voice. It's kind of eerie hearing Taylor talk; he sounds just like Tidus.
Different from the Japanese version of the game, where Tidus is voiced with fire and passion, Taylor decided to make Tidus more laid back, and "more of a dude." He made Tidus like his brother, who is super laid back, but is excited about life. That's how he said he saw Tidus.
Something cool about Taylor is that he actually related to the character of Tidus. He doesn't have a relationship with his father, and was able to pull from that to feel what he needed to for Tidus' role. He said he also likes to make everyone happy, like Tidus does, and he brought that part of himself to the character.
I know the Final Fantasy X fandom community is kind of split about Taylor's performance, but I think Taylor did an amazing job voicing Tidus. I like the versatility he brought to the character. In normal scenes, he was able to be peppy and excited, and in flashbacks and reflections, he was more calm and serious. This versatility made Tidus dynamic, in my opinion, and therefore believable.
To learn more about Taylor, or to find out what he is working on these days, check out his official site.