Below are my choices and why I chose them:
I chose these based on the gems I can claim from most of these. With 50 gems from the shovel and 10 from clocktower potion, I earned 270 gems from clan games.
Alternate choice for Clocktower potion is the Power potion. If you need them for CWL, take them instead.
I think 40 gems are more useful than a hero potion so don’t take it. 5 levels on heroes can barely be felt so I’d skip it.
If you still have a lot of lab to do, the research potion is worth more than 50 gems. Training potions are good because they save at least 50 gems if not 60-100.
Rune of builder elixir is good if you still need to unlock the OTTO. If OTTO is done, 70 gems are undoubtedly superior.
Builder potions beat both wall rings and the DE. Choose that.
The last row has the most interesting choices. If you still have a lot of lab to do, rune + book is the best. Since I have no use for elixir anymore, 100 gems are far better. If you can only choose one, take the book.