In this sutta the Buddha advises that the practice of metta and other brahmaviharas should be taken from the first to the fourth jhana. Specificaly, it recomends practicing equanimity from the first to the 4th jhana, proving that the Visudhimagga is wrong.http://www.accesstoinsight.org/tipitaka ... .than.html
So, just as metta can be felt during 4th jhana, upekha can be felt during 1st jhana. The Visuddhimagga has a very rigid (and wrong) classification of the jhanas.
Furthermore, In the most systematised way the Buddha taught the entire path, which is found in the Mahaparinibbana sutta, of the 37 things to develop to attain enlightenment, there is only direct mentioning of one brahmavihara: equanimity. Aditionaly, development of each brahmavihara leads to rebirth among the brahmas, and equanimity leads to rebirth among the highest brahmas.
Thus equanimity is the most important brahmavihara.
And, of course, if craving is your biggest problem, then you should apply equanimity and not develop metta then karuna, then mudita and only then upekha. It's self evident, imo.
He turns his mind away from those phenomena, and having done so, inclines his mind to the property of deathlessness: 'This is peace, this is exquisite — the resolution of all fabrications; the relinquishment of all acquisitions; the ending of craving; dispassion; cessation; Unbinding.'
(Jhana Sutta - Thanissaro Bhikkhu translation)