The finest music of Mahler IMO 
If by "the finest" you mean the most immediately appealing, the most simple (but not simplistic), the most childlike (but not childish), in the most vulgar yet the most effective orchestration, music Mahler ever wrote, then I do wholeheartedly agree.

Honestly, at home I'd rather take DKWH over any of his symphonies except 1, 3 and 4 every day and night. Imho, Mahler's symphonies are best experienced live in the coincert hall.