AAA is definitely about studio size and budget, it has nothing to do with the quality of the finished project. There are no clear rules for where the cutoff points between A/Indie, AA, and AAA lie, but generally speaking I'd say it's somewhere in this neighborhood as of 2018:
A/Indie- Team sizes between 1 and 40 devs typically. Budgets can range from just a few thousand dollars for 1 man basement projects up to around $10m typically.
AA- Team sizes between 40-100 devs typically. Budgets range from $10-50m typically.
AAA- Team sizes can vary widely, for instance Skyrim was made with 100 devs, one of the smallest AAA dev teams in recent years, while others, like Ubisoft, have been known to have over 1000 total devs work on a game at some point during it's development (with core teams over 400 devs). Recent known AAA budgets have ranged from $50m (LA Noire in 2011) to $265m (GTA V in 2013). Some other known game budgets for recent games that fall into that range: Darksiders 2 ($50m), Gears of War Judgement ($60m), Ghost Recon Future Soldier ($65m), Crysis 3 ($66m), Watch Dogs ($68m), Fable Legends ($76m before it was cancelled), MGS V ($80m), Witcher 3 ($81m), Skyrim ($92m), Halo 4 ($100m), Red Dead Redemption ($100m), Battlefield 4 ($100m), Tomb Raider 2013 ($104m), Max Payne 3 ($105m), Destiny ($140m).Last edited by shikamaru317 - on 30 July 2018