Consumables
In my experience in the 20's bracket, most of the potions and food scale in the same way, with a few exceptions (Nazjatar potions usually being the strongest). The difference would be what foods and potions are the easiest do create.
For
food, the Cataclysm's
https://www.wowhead.com/item=62649/fortune-cookie is a great option, as it gives good stamina and main stat.
For
flasks and
potions, the Draenor ones are the best, as they are easily mass produced by anyone with a Garrison. A honorable mention would be the Outland's
https://www.wowhead.com/item=22838/haste-potion, that can be a bit tricky to acquire.
***
High-level Heirlooms
In Party Sync, most gear effects are disabled, but all heirlooms can still be used.
Since some heirlooms require high-level, Party Sync'ed chars are the only ones that can use the
trinkets added in Warlords of Draenor like
https://www.wowhead.com/item=133596/orb-of-voidsight&bonus=0.
***
As always, if you want to Party Sync twink lookout for me in Tol'Barad and Nemesis. I'll gladly help you!