I think Gizmo is the more demanding role to play, and so far there have been only two hints of any relationships in the game - Rome/Widow and Gizmo/Senjo. Reaper is a much simpler character and just a thug really, though a creepy one. Gizmo works on more levels so he has more appeal to me though you should play who you feel you can bring to life best.<br/><br/>You'll need to read the whole game though to get a good handle on Gizmo which might be a lot of work.