That's me too. My technique and sound is much better on alto than Tenor (my Tenor altissimo is rough, and is what i would call "passable". On Alto it's much smoother, and dialed in).Me too. I played the same alto mouthpiece for 20 plus years until recently. It was relatively easy finding "the sound" I wanted when looking for a replacement. On tenor........ oh boy! I've gone through many pieces and still can't quite settle on one that is "the sound" that I am looking for. The oddest thing is that I enjoy playing tenor (where I can't seem to pin down "my sound") more than alto (where I have "my sound" exactly where I want it). I think the tenor is more of a challenge for me and that keeps me picking it up more than the alto, which came somewhat naturally to me.
It's the same for the horns. I have several tenor horns and just one, good old, reliable BA Selmer Alto that has served me well since the late 80's.