Well, separate from the question of whether the modern Tesla Cult is valid or not in its adulation of the man (most serious historians think not), Edison was exceptionally good as a personal myth-maker and self-promoter, and his economic power allowed him to broadcast (quite literally) the story about his greatness that he preferred. Like many a famous, wealthy, powerful person he strove to make sure that everyone knew who he was. He took personal credit for a lot of things he didn't personally do, he built up a vision of himself as a "lone inventor" that was romantically appealing in the American idiom, although patently false. His name was physically imprinted on a huge quantity of physical infrastructure (and still is today) that fill American cities.

It's hard to compete with all of that. The glorification of Tesla is probably its own story, but falls outside of this subreddit's periodization bounds (too recent, on the whole). I do not think it is coincidental that the people who love Tesla are often the same people who think that technology is about "innovators" who swing a wrecking ball through society in a "disruptive" fashion and magically change the world. But this reading of Tesla is not a historically accurate one — it is its own form of myth-making.

For a serious take on Tesla that gets beyond the death-rays-and-free-power hype, see W. Bernard Carlson, Tesla: Inventor of the Electrical Age (2013), which is very balanced in its assessment, by a proper historian of technology. Paul Israel's Edison: A Life of Invention (2000) is the standard reference on Edison's own "invented" life.