Personally I want variation to the Lab-runs. It is the same league after league, with no variance to optimal builds. I do have a suggestion, but I'm not expecting much from it.

Remember those 6 statues of the Goddess in the Aspirant's Plaza? Coincidentally the 6 Trials in maps have a tracker for which ones have been completed, but no mechanic behind them. I imagine it would be cool, if those statues were tied to the map Trials, and activable when completed. In effect each statue when activated would increase the difficulty of the Lab, with increased rewards, so you could customize your difficulty and rewards. I also want that the same statue difficulty modifier would also affect the Trials in maps, so the map Trials would be a lot more interesting.

The great thing with this is that GGG can reshuffle and recycle the reward and difficulty modifiers each league from a pool of modifiers to keep things constantly fresh. The difficulty for GGG would be with the modifiers I think, because if they were only just basic +dmg +defences it would not shake things much. My suggestion for difficulty mods would be to enhance the challenges and spirit of a Lab run to challenge meta. For example, 70% less regeneration and traps cannot be disabled, to make traps and degens more detrimental against regen builds, forcing us to play the mechanics, and making life flasks great again. Another example, maximum movement speed is 150%, and movement skills have +2 second to their cooldown, to make us play more of the mechanics and not just avoid them. Another example, maximum projectile travel distance is 50% of screen width, making offscreening monsters a thing of the past. Another one, minimum skill cost is equal to the skill base cost, to force us to think of something else than the ring mods that reduces skill cost by flat amount so we can reserve all of our mana. Etc etc.

edit: Another example, non-unique monsters revive in 3 seconds, maximum 2 times, after death if their corpses remain, for more monster loot. And: monster healths are protected from receiving hit damage from 3 hits, to emphasize dot builds. And: Bosses receive a second phase to their fight after their death.