Big Bang (Korean pop), Hikaru Utada (Japanese pop), Lady Gaga are the big 3 in my playlist. A little Queen is always good too - Another One Bites the Dust is an excellent workout song. The better the beat, the better the workout song in my opinion, particularly for cardio. For weights sometimes I get a little more introspective and slow it down a bit, but generally speaking I need fast peppy songs to keep me going.