[usedranger]

Just like engine oil some brands have a few more additives than others. And most shadetree mechanics develope a favorite. One guy likes Valvoline another Castrol. Some add conditioners (me I add Lucas) others don't. The important thing is to do the change.
Most chain autoparts stores have their store brands like Walmart. Whether they used a name-brand or Toyota trans fluid may not make as much difference as does the kind of driving you do and the location. Hills vs flat, for instance.
At some point you will have to drop the pan and change a filter. If you have been doing regular changes at the dealer your transmission is probably getting the attention required, and may have had a filter change. Check back on your reciepts or ask them. Most have the information in a computer database. Good luck.