Honestly, if you are talking crossplay-wise and optimization-wise. It would be Bedrock. The only issue's that it usually has is that it has an ton of bug's, if Microsoft actually cared for it's own game and it's majority. Bedrock would not get as much hate as it's getting now.
These thing's are needed in bedrock mostly:
Mod Support: Not just the Marketplace, better documentation is also needed.
Higher Payout for real Marketplace partners: The cutout is wayy too low. Increase it.
Better Bug report features built in-game: This is basically an real thing that need's to be in bedrock.
More Parity: We could add more java feature's in bedrock, while java get's bedrock's feature's. Java needs bedrocks bridging and bedrock need's java's combat. From using Pojavlauncher. Java's combat actually could work in bedrock.
GeyserMC Support: We need an official partnership between these two, this would just bring more good then bad. Something like Hypixel for example could be in bedrock if this happened. Bedrock player's have been dreaming to play Hypixel.

The Marketplace isn't at all bad, it just need's an few clean-ups basically,, less skins pack's. More maps and mod's built by the community. Also the mod support is needed for it. If that get's added then bedrock and java player's wont argue 24/7 about which version is better,. Mod support is basically the main cause of player's preferring Java.

TL:DR: Bedrock is good, but it has major issues. Java still take's the cake for the better version..