In regards on what L2 you choose for safe bridge, No one can answer you here an exact answer since all of the existing bridge has the tendency for potential exploit due to a lot of factor.

Each L2 have their own trusted bridge. I think the greater the liquidity on the bridge means the more safety you can use it because already a lot of user trusting it. The danger on bridge relies on the liquidity provider while the user is rarely become affected because you are just using it not too frequent.

L2 has their own advantages and disadvantages so it’s up to you on what kind of protocol do you preferred but the safety is always subjective because no one knows what project will be the target for exploit.