The problem here will be that not many people have tried Dr.Web Security Space to be able to provide you with a balanced feedback. Even I haven't, except for its on-demand tool 'CureIt'.
'Malwarebytes 3' has gone heavy and even now, not considered effective against a range of malware, though it claims to be a complete security suite.
I have seen 'Dr.Web Security Space' in action in our Malware Hub and surprisingly, it covered a range of threats, though the system was usually being infected (I don't think that it will be the opposite for MB either).
For Dr.Web, you can refer
@Der.Reisende's December 16 - January 17 testing in MalwareHub. He might be able to give you some more idea about the product's overall effectiveness.
The best way is to try them out since unbiased tests on comparison of the two are rare to find. In my opinion, both of the products are NOT ENOUGH as STANDALONE protection.