I can't help but think that Mozart's ""Lacrimosa Dies Illa" is objectively the most exquisite, pristine, and powerful pieces of classical music ever orchestrated.
I cant deny that Mozart was possibly the most talented composer and even by a significant margin. I say possibly because he died as his career was seeing exponential growth, in the midst of his best work. However I think that altogether the development of music in the romantic era brought about a greater degree of expression and I think its a bit presumptuous to say music hit some sort of objective "peak" at the end of the 18th century. No doubt Mozarts music is beautiful but there are entire musical concepts missing from his repertoire. Personally I prefer Beethoven to Mozart but I feel strongly that had we been living in a universe where Mozart lived a full life it would be criminal to say such a thing.