CC Ādi 4.214

sei gopī-gaṇa-madhye uttamā rādhikā
rūpe, guṇe, saubhāgye, preme sarvādhikā
Word for word: 
sei — those; gopī-gaṇa — the gopīs; madhye — among; uttamā — the highest; rādhikā — Śrīmatī Rādhārāṇī; rūpe — in beauty; guṇe — in qualities; saubhāgye — in good fortune; preme — in love; sarva-adhikā — above all.
Translation: 
Among the gopīs, Śrīmatī Rādhikā is the foremost. She surpasses all in beauty, in good qualities, in good fortune and, above all, in love.
Purport: 

Among all the gopīs, Śrīmatī Rādhārāṇī is the most exalted. She is the most beautiful, the most qualified and, above all, the greatest lover of Kṛṣṇa.