its all personal preference. ur post confused the hell outta me. altos are in the key of Eb which probably means nothing to you. tenors i believe are 4 steps below alto.. which would make it Ab? nawww.. but i kno its 4 steps below. its personal preference tho dude. ive heard people play notes on tenor, that i cant even finger on alto w/o alternate fingerings. and even then i cant play em. theres no specific "mood" to alto or tenor. u can play whatever u want with either horns.

tenor is in the key of Bb. When you listen to sax music, which sound do you like more? that's the only criteria. i say this from experience with the same dilemma you're having. I've played tenor for 16 years but at times recently I thought alto might be a good horn to try because I'm not a big guy and I thought, well maybe because the alto's smaller it will take less breath and the fingerings will be easier and lighter, making fast passages easier. common sense right? so last summer I got a good deal on a good alto and, well, it wasn't true, at least not for me. how fast you play is all about how much technical stuff you practice (think of all the great tenor and even bari players who fly up and down their horns) and not about how big your hands are. and it's true that tenor takes a little more breath, but that's offset for me by the fact that alto requires a tighter embouchure and more activity in the vocal cords. Ultimately, after 16 years, I have the tenor sound in my head, but I also like that now I can play alto as a "change of pace" and there are certain situations where I prefer its sound to that of a tenor. but it's nothing as obvious or general as "tenor is my moodier horn" or anything like that. so I say just listen to as much as you can (this is the biggest key in learning any instrument in any style of music) and find where your ears and heart gravitate to the most. hope this helps, Miguel.