If you are intending to buy a PS2 for only playing games off the HDD unit, any fat PS2 will do. In that case, an unmodified console might be preferred as modchips might interfere with some homebrew software.
Originally Posted by plandr
If you intend to play CD/DVD games with the optical drive on a regular basis, you might want to avoid those SCPH-5x000 series consoles as their lasers.... burn out more easily (Especially when modded). D:
The SCPH-10000, SCPH-15000 and SCPH-18000 are very rare, early consoles. They only support the PCMCIA Network Adaptor and external HDD unit, and are quite good in terms of construction.... but their lasers might not last too long (Especially if you consider their age and the hardware design). Part replacement is a pain.
SCPH-10000 S. MINOKAMO v1.01 (Defunct)
SCPH-10000 S. KISARAZU v1.00 (faulty)
SCPH-15000 S. KOHDA (With warranty seal!) :D
DESR-5100 S. EMCS