There is no number one arsenic removal water filter system out there. I recommend doing your research and determining what is best for you. For instance, if you get your water from a well water source, you might want to consider an oxidation filter, which will remove arsenic and common well water contaminants.
If you’re just looking for a water filter system that purely removes arsenic, your options are endless. Focus your search on filter systems that are NSF certified to remove more than 95% arsenic for the best results.