Food:
Blackened Dragonfin (Agi),
Dragonfin Filet (Str),
Firecracker Salmon (SP, there are other equivalent recipes for casters),
Blackened Worg Steak (Track Humanoids).
Fish Feast is best for casters, but needs more mats.
See also all secondary stat recipes
here.
Flasks:
Flask of Endless Rage (AP),
Flask of the Frost Wyrm (SP),
Flask of Pure Mojo (Versa),
Flask of Distilled Wisdom and
Flask of Supreme Power are
notably better for casters and are the ultimate BiS flask. However, they require Black Lotus, a notoriously rare herb, so are likely much harder to obtain.
There may be some Elixir combos that would theoretically be slightly better, but the fact that flasks persist through death makes them superior.
Potions:
Shared Cooldown:
Haste Potion (15s 245 haste, about 2/3rds of a Bloodlust),
Free Action Potion (24s of stun/root/slow immunity),
Swiftness Potion (15s of 50% runspeed),
Major Rejuvenation Potion (the mana restore is very beneficial for hybrid classes that have innately small mana pools, like Ret/Prot paladins, Enh/Ele shamans, or Balance/Feral druids),
Potions that do not share a cooldown with the above 4:
Runic Healing Potion,
Healthstone (you don't need a warlock - simply queue for the Proving Grounds from your class trainer and you can get one, then leave the PG).
Weapon Enhancements:
Adamantite Sharpening Stone /
Adamantite Weightstone (Melee DPS, 9 dmg + 7 crit),
Superior Wizard Oil (Casters, 32 Int),
Superior Mana Oil (All classes/specs, 20 versa).
Remember that you can mix and match the sharpening/weightstones and the Mana Oil if you dualwield, depending on your preferences. I personally use a weightstone on MH and Mana Oil on OH on my Enh Shaman.
Others:
Noggenfogger Elixir (Being tiny makes a difference. Play a Tauren Priest and then a Gnome Priest and see for yourself
. Joking aside, it's generally not useful against good players, but does provide 2 trash debuffs to protect against purge/dispel/spellsteal. The average leveler is
definitely less likely to target you with this on, which is still great.)