There are some statements in the vedas which might give scope to an interpretation of the existence of ranking among deva-s.
Aitareya brahmana 1.1.1
agnir vai devānām avamo Viṣṇuḥ paramas, tadantareṇa sarvā anyā devatā
Agni is the lowest of the deva-s and Vishnu is the highest. Between them are all other deva-s.
Madhvas interpret the above statement as a ranking among the deva-s.
A similar statement is found in Taittiriya samhita 18.104.22.168 -
When about to consecrate himself, he offers to Agni and Visnu on eleven potsherds; all the deities are Agni; the sacrifice is Visnu; verily he lays hold of the deities and the sacrifice; Agni is the lowest of the deities, Visnu the highest; in that he offers to Agni and Visnu on eleven potsherds, the sacrificer envelops the gods on both sides and wins them.
In the above, the talk of enveloping the Gods on both sides may hint at the other Gods being in between Agni and Vishnu.
That Agni is the lower end of the Gods and Vishnu is the upper end, and all other Gods are in between, is also hinted at in Satapatha brahmana 22.214.171.124 -
And on the following day he prepares a cake on eleven potsherds for Agni and Vishnu, and offers it in the same way as the (regular) ishti: this indeed is just what that approved initiation-offering to Agni and Vishnu is there 2. Now Agni is all the deities, since in Agni one offers to all deities; and Agni forsooth is the lower end, and Vishnu is the upper end: 'May I be consecrated, after thus encompassing all the deities, and after encompassing the whole sacrifice!'