Recommended FAT model?

Hey.

I'm considering of getting rid of my V12 Slim PS2 and get one that allows me to install a HDD in it (I have no interest in HD PRO).

I do not want to chip the console, I use FMCB/OPL (or SwapMagic for OPL/ESR incompatible games), and Breaker Pro for PS1 games, so I still want a reliable laser.

After doing some research it seems the best models are either SCPH-3900x or SCPH-5000x, but I don't know which one is the best out of the two.
Could anyone enlighten me please?

Thanks in advance.