BIP101 > BIP100 > 1 MB
The biggest problem I see with BIP100 is the 21% attack. 51% of the hash power can already effectively limit the block size by orphaning any block larger than Q_max. Why would we want to make the network more susceptible to this attack vector? However, assuming the BIP100 proposal is adjusted to use the median vote (or something similar), I find BIP100 tolerable although far from ideal.
To me, BIP101 is based on the ideology that the limit is an anti-spam measured (it's original rationale) and thus should be so far above the average transactional demand that its economic effects are negligible. BIP101 helps us to gradually transition into the unlimited block size scenario.
BIP100, on the other hand, seems to hand additional power to miners to use the block size limit to distort the natural fee market. With BIP100, I suspect we would end up with both higher fees and slower growth than we would with BIP101, all other variables equal. If miners want to coordinate a lower max block size, why don't they do it with a soft limit on top of BIP101?