Lasso was no doubt the greatest Renaissance composer, fluent in any style of the time: Villanella, Chanson, Motet, Madrigal, Lied, Hymns, Lamentationes,... And he was fluent in French, Italian, German and Latin, too. Over 2000 secular and spiritual works have survived to this day. Many another composer would envy both his productivity and the care with which his works were kept for posterity.
What I like about his music is, for one, the polyphonic Renaissance style in itself, but most of all I like its diversity: Four different languages and many more styles. There are sad songs of love, sacred music, hilarious songs about the joy of life, or satires, all put to music that characterises the content of the text in a way that can be instinctively understood. I guess that many people would be astonished to learn how funny and even indecent many of the texts are.
If you want to put an ear to Lasso's music for the first time, I recommend To All Things a Season by The King's Singers on EMI CDC 7 49158 2. It is a fair collection of Italian, French, German and Latin, of funny and sad songs. A number of the more humourous (even a bit naughty) madrigals can be found in the MIDI archive. "Matona mia cara" is one of my all-time favourites.