Return to the world of Kanto originally explored in Pokémon Red and Pokémon Blue, where the adventure is brought to life better than ever with dazzling GBA graphics and dozens of surprising new features
Going by personal preference, I would say Fire Red. But I think Leaf Green is better since you get Deoxys in it. I am not exactly sure since I haven't played any of them.
Since there is no more debating on this subject and this Thread i'll Lock it. The creator of the Thread can P.M me to re-open this or someone can create another thread of this type, but keep it to the subject or else that may get locked too.