The devotees who have developed love of Godhead are certainly in an exalted position.
Of all these devotees, the gopis are recognized as superior because they do not know anything other than satisfying Krsna. Nor do the gopis expect any return from Krsna. Indeed, sometimes Krsna puts them into extreme suffering by separating Himself from them. Nonetheless, they cannot forget Krsna. When Krsna left Vrndavana for Mathura, the gopis became most dejected and spent the rest of their lives simply crying in separation from Krsna. This means that in one sense they were never actually separated from Krsna. There is no difference between thinking of Krsna and associating with Him. Rather, vipralambha-seva, thinking of Krsna in separation, as Sri Caitanya Mahaprabhu did, is far better than serving Krsna directly. Thus of all the devotees who have developed unalloyed devotional love for Krsna, the gopis are most exalted, and out of all these exalted gopis, Srimati Radharani is the highest. No one can excel the devotional service of Srimati Radharani. Indeed, even Krsna cannot understand the attitude of Srimati Radharani; therefore He took Her position and appeared as Sri Caitanya Mahaprabhu, just to understand Her transcendental feelings.
From Srila Prabhupada's purport to The Nectar of Instruction, verse 10