To call any show "the best of all time" is much too subjective but Lost is the best show of the millennium without a discussion..you'd have to consider
drama versus comedy etc to justify which is the best ever (MASH in it's time was unparalleled). The critics who gripe about the finale either didn't watch the series closely or should have watched it multiple times, you see
"Easter Eggs" that tie up things many of us missed the first time, the show requires certain leaps of faith and no hard core critic would have been happy with any ending. The characters are all endearing, the "bad guys" are great, it's got comedy, cliff-hangers, action, drama, romance, suspense and there has not been a show even close since 2010 when it wrapped. Watch LOST and keep an eye on the background of many crowded scenes when you do, or you'll have to watch it again before the finale