Among the gopīs, Śrīmatī Rādhikā is the foremost. She surpasses all in beauty, in good qualities, in good fortune and, above all, in love."
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.

(Sri Caitanya Caritamrta-----1:4:214------purport).

Of all these devotees, the gopīs are recognized as superior because they do not know anything other than satisfying Kṛṣṇa. Nor do the gopīs expect any return from Kṛṣṇa. Indeed, sometimes Kṛṣṇa puts them into extreme suffering by separating Himself from them. Nonetheless, they cannot forget Kṛṣṇa. When Kṛṣṇa left Vṛndāvana for Mathurā, the gopīs became most dejected and spent the rest of their lives simply crying in separation from Kṛṣṇa. This means that in one sense they were never actually separated from Kṛṣṇa. There is no difference between thinking of Kṛṣṇa and associating with Him. Rather, vipralambha-sevā, thinking of Kṛṣṇa in separation, as Śrī Caitanya Mahāprabhu did, is far better than serving Kṛṣṇa directly. Thus of all the devotees who have developed unalloyed devotional love for Kṛṣṇa, the gopīs are most exalted, and out of all these exalted gopīs, Śrīmatī Rādhārāṇī is the highest. No one can excel the devotional service of Śrīmatī Rādhārāṇī. Indeed, even Kṛṣṇa cannot understand the attitude of Śrīmatī Rādhārāṇī; therefore He took Her position and appeared as Śrī Caitanya Mahāprabhu, just to understand Her transcendental feelings.
In this way Śrīla Rūpa Gosvāmī gradually concludes that Śrīmatī Rādhārāṇī is the most exalted devotee of Kṛṣṇa and that Her kuṇḍa (lake), Śrī Rādhā-kuṇḍa, is the most exalted place. This is verified in a quotation from Laghu-bhāgavatāmṛta (Uttara-khaṇḍa 45), as quoted in Caitanya-caritāmṛta:

yathā rādhā priyā viṣṇos
tasyāḥ kuṇḍaṁ priyaṁ tathā
sarva-gopīṣu saivaikā
viṣṇor atyanta-vallabhā
"Just as Śrīmatī Rādhārāṇī is dear to the Supreme Lord Kṛṣṇa (Viṣṇu), so Her bathing place (Rādhā-kuṇḍa) is equally dear to Kṛṣṇa. Among all the gopīs, She alone stands supreme as the Lord's most beloved."

Therefore everyone interested in Kṛṣṇa consciousness should ultimately take shelter of Rādhā-kuṇḍa and execute devotional service there throughout one's life.

(NECTAR OF INSTRUCTION).