Element monks outpace EKs and ATs. AT/EKs get 2 1st level spells "per day" at level 3. Elemental Monks get 3 ki per rest so 3 burning hands a day. (with 2 shorts per long that's 9 ki "per day").
At level 7. it's 4/2 for the AT/EK and monks have 7 ki per rest (good for 1 2nd level burning hands and 2 1sts).
The issue is that monks really don't have many features to differentiate themselves once out of ki. The general monk options are all cosmetic from level 5 (unarmed, daggers, shortsword, or staff). And of the most played levels of D&D (lower level), the subclasses grant more ki uses to fret over. The Shadow monk is best as it at least grants a cantrip and shadow step. The Element Monk is a ki-addict and the Open Hand monk encourages FoB spam.