There were no musical instruments around at home nor have I come into regular contact with muso types, so most of my learning and enthusiasm has always largely been self taught or self motivated.
I always feel a bit bitter when I think back to the lack of peripatetic musical instrument teaching opportunities at the school I went to for the majority of my primary and all of my secondary education. One key incident in particular, in our 4th form year when our music lessons for that entire year were cancelled so that the music teacher could concentrate on giving the school's star music pupil private tuition whilst our form had to do non music related private study in the meantime instead - this turn of events prevented our year from taking the GCSE music exam the next year as we had obviously missed out a whole year's worth of syllabus teaching!
We were taught descant recorder at my first primary school but that didn't last long as I only spent 2 years at that school and that was pretty much the end of that when I moved schools.
At the new school I had flute lessons for two years until the school's main and only music teacher who was providing the lessons left and her replacement wasn't able to teach us so that was that. Never actually took any exams on the flute so not quite sure of my standard, but whilst working in London I participated in a flute group evening class for intermediate/improver level flautists and was told that I was about grade 4 or 5 standard.
Just after finishing university and just before taking up the flute again, I joined a piano evening class group. I've only ever had any experiences of private instrument tuition just more recently, and only went the private route because there were no other opportunities available locally for teaching beginner/intermediate level instrument playing in groups. The group piano lesson evening class was the most fun thing I've ever done as an evening class. Each weekly session of the piano evening class was 2 hours long and there was about 10 of us in the group (out of a possible maximum of 18). Obviously with one-to-one private tuition you'd progress faster and learn more rapidly, but even so I managed to get a few exams under my belt during the 4 years I attended that group. One unique thing we all gained out of the group and something that the tutor and his subsequent successor were both very keen on was the ability to improvise - something which is far easier and a lot more fun and interesting to learn when you do it in a big group rather than as a one-on-one exercise. So yes, the answer to the original question is I consider the piano as my main instrument. One of the stumbling blocks I have, besides the motivation to practice is that of learning new repertoire. Due to eye sight problems, it's not really practical for me to sight read music in real time whilst playing, but if I were to be honest my sight reading is really bad anyway because I've never bothered to get it proficient enough in the past rather than because I can't see to do it properly par se. I think sight reading music would feel more natural had I learnt it at an early age. So even though I've actually taken up to and including the grade 4 exam for piano, I always get by by remembering and playing all the music required for the exam from memory. Unfortunately, my ability to rapidly memorise and replicate a piece of music I'm listening to and be able to play it back on an instrument isn't all that great either. Having said that I do much prefer playing by ear and am certainly not one of those people who are completely and utterly lost unless they have a sheet of music in front of them - that seems very odd to me!
I've also tried having lesson on the guitar and euphonium, but neither lasted long as I found that I just wasn't getting enough practice in each week to make the lesson worth while, again these were evening class activities. So about the only type of instrument I haven't tried my hand at yet is a bowed string instrument. I don't know why, but I reckon strings are about the hardest to get started on IMO, it's the lack of fret markers that makes me think that these instruments must be incredibly hard to play in tune (especially in an ensemble situation), plus the bowing technique must take ages to perfect before you can get any type of musical note out of it!
Never played in a band before as not really been competent enough or had the opportunities to do so in the past. Oh well, one day, better start getting some more practice in I suppose when I get the time!
Listening to other people play and appreciating their skills can be an awesome experience, but being able to make your own music too is satisfying in a different way; it's the self-effacing and self-expressing art of it that is special IMO.