I've recently started yet another rewatch of Toradora! and I found a few anibrands to share, starting with this bottle of Toriaezu Ocha that can be seen in a vending machine in episode 4.
It is based on the real-life brand Oi Ocha from Itoen, which is a very popular brand of unsweetened green tea.
A bottle of Oi Ocha
A bottle of oolong tea can also be seen in the vending machine, but tracking down the exact bottle it's based on proved to be quite difficult. I believe it is based on a 500ml bottle of Suntory oolong tea from 2008, but the only pictures I found were very low quality so I had to upscale and clean them.
A bottle of Suntory oolong tea
Also interesting to note that I have encountered Toriaezu Ocha in another series before, namely Golden Time, which happens to be based on a light novel by Takeyama Yuyuko, the same author as Toradora!. Both series were animated by J.C.Staff, so it isn't surprising that they would reuse the same anibrands.
A can of Toriaezu Ocha as seen in episode 19 of Golden Time