mono block or bi-amps which would you pick?

Bdp24... using two stereo amp driving the highs and mid with one amp and the bass with a different amp.  

2 mono amps
 -  being close to the speakers you significantly shorten the distance traveled over speaker wire resulting in less entry points for distortions....AND....
 - since the length is shorter, you can opt for better-sounding speaker wires that may cost more than you'd otherwise be able to afford for long runs from the amp.

I went from stereo to monoblocks and never looked back so, mono it is.

Another vote for monoblocks. I will never go back to stereo again.

If there are mono amps of which you can afford four, you can bi-amp with mono blocks. But not all speakers benefit from bi-amping, which has more to do with the speaker's crossover than the amps. And not all speakers CAN be bi-amped. Many bi-ampers like to use a tube amp for the midrange and high-frequency driver(s), and solid state for the woofer(s), while others like to use identical amps. Do you plan to use an outboard electronic x/o? Bi-amping is more involved than just using two stereo power amps.