It's also based on familiarity.
Core-A Gaming did two videos on why people use different controller setups:
https://www.youtube.com/watch?v=vbT3UR5O1YQ
https://www.youtube.com/watch?v=fzIYidgQeFI (First portion features clips of the man of the hour himself)
If about 15 minutes of videos is too long, the TL;DR version is essentially that
1. People use different setups based on familiarity; U.S and European players tend to play on controllers, whereas Asian players that grew up playing in arcades tend to use sticks.
2. Comfort; Some movements like charge motions are more elegant on Square Japanese stick gates, but controllers and American sticks are much easier for doing literal quarter-circle motions.
3. Usability; This one's covered a bit more in the second video, but arcade sticks allow for much more customization than first-party controllers (both in terms of cosmetics, and tactility), but also suffer from being after-market, and sometimes being shut-out, or penalized by the consoles themselves from being detected as such.
Overall, it's a mixed bag. If you play Tekken and are considering switching, play on console with what you're used to, then play in an arcade, and feel out what's best.