Beartic is solid. Gothitelle is good, but way too vulnerable to be T1. Other decks in the past that have been considered T1 (Luxchomp, Dialgachomp, Yanmega/Magnezone, Stage 1s, Dialga G/Palkia G, Horsemega) have outs to almost any situation. If Gothitelle comes up against a Mewpluff, Xatu (even though it's an inferior counter), Beartic, or even a Bellsprout, the deck self-destructs.
IMO, the tier list will look something like:
TIER 1
Stage 1 Variants (lots of playable Stage 1s to choose from)
MewPluff Vileplume
Zekrom/Tornadus
TIER 2
Magneboar
Reshiphlosion
Gothitelle
Beartic/Vileplume
Horsemega
Ross' deck
TIER 3
Donchamp
Scizor (on the backburner until Kyurem is released)
Steelix (on the backburner until Kyurem is released)
RDL Rush
Reshiboar
Disclaimer: If Gothitelle takes a lot of BRs, it's because of the hype surrounding it and popularity, not because it's a Tier 1 deck.