I use a metal dog comb for all my animals (dogs, cats, rabbits, guinea pigs). Double sided ones can be useful for fur that tends to mat, just to get it started with the wider spaced teeth, otherwise just the normal comb will pretty much do everything. You need to get down to the base of the fur, so combs do a better job imo. Brushes tend to not get right down to the skin. Just doing the surface layers means that loose undercoat stays there.
My smaller furries are all long haired and get groomed once a week normally, maybe twice if they are having a full moult.