I have been using blockchain wallet for bitcoin for the last five years. It is very secured to me because i use all of the security actions including mobile sms, email verify, back up key, 12 backup pharase, password, google authenticator combinedly. So blockchain is the best secured to me and i will use blockchain for bitcoin wallet as long as i can.
You are right, blockchain.com provide many features to secure the access to your account, still, it's an online wallet and should not be trusted.
Even if you keep your passwords/seeds safe, you can't be sure that their servers/platform are secure too (this is not something you can control). Also, there is no way to verify that they don't keep a copy of your seeds.