Okay, so not “top block producers”… but just “largest wallets”.
In which case, that applies to almost every project in the space right now. BTC included. Every project is centralized right now, because we’re in the infancy stages, and early token distribution is poor. However in time, hopefully tokens will become more evenly distributed. Not saying they will, but in theory that’s the underlying basis for which most projects in the space have constructed their consensus mechanisms.
Also hopefully people will also quit leaving their tokens on exchanges (thus avoiding giant Binance wallets). In Cardano’s case, this is due to the fact that most people are waiting on the upcoming Ledger support before moving their tokens into cold storage (myself included).
Point being, the arguments I’m making are based on the intended proper distribution (which is a far more interesting topic than EOS vs ADA). If that were to happen, Cardano would be virtually impossible to attack. The same cannot be said about EOS, as it will always have a central point of failure due to the fact that they don’t offer immutability. However that’s something they willingly chose to implement by design, and although I think it renders EOS worthless, clearly some people feel it offers value (and that’s okay!).
Another thing to add, is that unlike PoW where you can attack using raw hashrate, PoS requires that you own a very large holding of whatever asset you’re attacking. That means that you’d have to invest an obscene amount of money to obtain sufficient authority, and then self-sabotage the network along with all your holdings on it. It’s possible, yet completely illogical, to the point where it renders this entire discussion rather pointless.