Greens singers may be the best choice of the three but a good singer canary will put them in the shade, and a skylark would blow your mind; at least, it blew mine.
Many of your neighbors would no doubt enjoy the birdsong, but there is always one complainer in an apartment block.....
Avid amateur aviculturalist; I keep mostly australian and foreign finches. The art is long, the life so short; the critical moment is fleeting and experience can be misleading, crisis is difficult....... (Hippocrates)
do not compare greensingers song with the yellow siskin (assume you mean YHS), green singers are very good and also very loud, so if your wanting to peeve your neighbours go right ahead but you have to question your motive for having a song bird. Yellow Hooded siskins also sing exceptionally well but are much different in their song and depending on where they learnt their song it will ususally have some mimicry included in it as well. Also their intensity wil vary in between breeding season and non breeding season. Two separate birds two separate songs, too good to have just to annoy a neighbour.