Searching for a simple Queens Gambit Declined line for black

Are there any "bulletproof" lines you can recommend?

Just play whatever Stockfish plays at top level. Shouldn't that be good enough? (:-)

Tartakover Variation. Easy and sound position then the middle game is rich.

Really interesting with hanging pawns. Watch Kasparov karpov world championship.

I know you said declined, but the QGA is really not a bad opening - and you tend to get White into positions they may not know quite quickly. Just throwing it out there.