All 12 traits in all 3 tiers but ...
My bad I just saw this post convincing me this will never make it in to the game.
https://forum-en.gw2archive.eu/forum/info/news/Balancing-Guild-Wars-2/first#post92064
This won’t work since some traits are things like “wells now use ground targeting”
It would also imbalance PvE and PvP and lead to less build diversity
It can work for sure just needs some thought put in to it but I gave up on idea earliest it would get implemented would be in expansion if ever.
They’re hardly going to completely rework and rebalance the entire trait system at this point, and suggesting that they do so is kinda ridiculous. I also don’t really see how your suggestion would be an improvement at all.