relation of a halogen radical's reaction properties to those of -OH

hunter111112

So on my test in organic chemistry one there was a question i did not know how to approach. Which halogen would react most similarly to -OH (we were discussing SN1,Sn2,E1,& E2 reactions) and why can you make this correlation? I have missed no classes but can't seem to find information on this anywhere. Any help would be appreciated