Heck, there are people who still use motor oil.
But once TranSynd was invented, everything else became obsolete.
Kind'a like... you can debate the merits of KodaChrome versus EktaChrome, and various Fuji films -- some of us swore by Fuji Velvia. And it all became moot when digital photography was invented.
TranSynd is expensive, and worth it.
Other brands exist and are acceptable, so long as they meet the TES 295 standard (which you can see on the TranSynd can label). But TranSynd dominates the TES 295 market.