Clarinet, Sax(Alto/tenor), Trumpet, Mellophone and French Horn.
My main is the French Horn, so much more difficult than the rest since there are so many partials. It's like singing with no accompaniment, you have to memorize how the notes sound like in order to produce the correct note. Also, the instrument is 30ft long when extended, a lot of air pressure is needed. And it also has the smallest mouth piece of all the brass instrument which means a lot of pain to the lips, so even if you want to practice a lot to get better, you're highly limited in time to the strength of your lips...