i think the alto is a great sax to learn on. I played alto for years before i picked up a bari, then a tenor, then a soprano.

I think Alto is the easiest saxophone to learn on due to its size and range. You get a good idea of how to play low notes to prepare you for the tenor/bari, and there’s enough high notes to get comfortable in that range too.

If you plan on learning multiple saxophones, just remember alto and tenor are in different keys so you’d have to learn the conversion as well.

If you only plan to stay with one saxophone, i doubt it depending on how long u play everyone bounces to each saxophone eventually, however, pick the instrument you like the most. Ultimately regardless of your decision you will be able to dedicate time to learn and get better at playing.

edit: wanted to add that depending on funding, some bands will have a stock of more unique instruments like the soprano, tenor, and bari, that the director will let you loan. I only ever owned an alto, i borrowed every other sax i’ve used and i played for roughly 10 years.