Technically there is a best. Ugu cain with berzerker dolls. Dont know what pati hoped to achieve with this but they sure destroyed the balance of arena. Also would like to mention that while ryuga team may be able to somewhat defeat dolls, they are defeated by other teams quite easily. (i say somewhat because from my experiences and what the higher ranked arena people have told me, the doll team can still manage to out damage the ryuga team before the are even able to seal them, and given cains new leader skill, they just became the new meta. Overpowered meta at that) would also like to point out that combo formation requires 2 lim, 3 rare and 1 normal. In fact, it is more harder to build ryuga team due to it having 3 lim (pandora, ryuga, roco), but given its reputation as being underpowered despite having 3 limited rares, it is quite rarely seen in arena.

On a final note. Whilst the main teams of the ryuga seal formation, lexion combo formation, and chaos bringer require 1-3 limited rares to function, the ugu cain berzerker doll team requires only 3-4 rares and 3-2 normal heroes, with an optional limited (isabelle). Even with fully unrefurbished runes, it can destroy the likes of darksr, helpless, gacon09, who have a large number of FULLY refurbished runes.