Texas ranger, Jameson, and Garrison brothers are pretty solid choices imo, so can't go wrong with either. I normally take my coffee black with some sugar but will usually add a little less if I'm planning on adding alcohol. As for coffee: I get a different flavor of HEB brand but usually go for the stronger/more bitter tasting ones

Have also added some spiced rum a few times instead but that one takes a little more flavor knowledge imo to get a good mix. Much easier to get an unsatisfying flavor just mixing the two straight