I recommend an original PS1, from experience, altough if your CD is scratched it can crash more than on a PS2 I think. On the PS2 the sound quality is the same and the memory limitations too, plus you can only save your songs on PS1 memory cards. But loading new samples can take up to 1 minute instead of like 2 seconds on a PS2, so the wait can be incredibly long sometimes. Besides that everything else seemed similar.
I personally use a PS1 emulator on my PC (same quality than on PS1, except that the click and pops you hear between low treble samples are louder sometimes)