My vote is for MP3's..I use the format with a laptop. This system is far superior than the other systems.I use Sonic Foundry software to record[wave] and render as MP3. I use 192 bitrate, but even 128 is CD quality..I can not tell any or very little difference between wave and MP3..With MP3 I can edit, change keys, change tempo, with Acid Pro[Sonic Foundry]. The space saving ratio is 10 to1 in favor of MP3[Data verses Audio]..With the laptop you can organize thousands of songs with full names and key info. They can be displayed around 100 tunes on a page. you can quickly scroll and find any MP3 in seconds. All this on a bright readable screen..You can quickly set up break tunes when your off stage..This system allows you to record your music and backup vocals for your shows, allowing you to play along and sing lead with your MP3's..The Mini Disc sounds good but does not have the same benefits, likewise with a CD player..