hi appiez, get a roomba if you wan to 'sweep/vacuum' your flr quite frequently, like 2-3 times a week. With the auto return to home base, roomba is more 'automated' than a scooba in that sense, require less human intervention
For a scooba, though it preps the flr, b4 washing, you will still hv to help it refill or clear dirty water and maybe charge it, so it will still require a certain degree of human intervention, plus it doesn't have a docking base. Also, your startup cost of trying a robot vacuum/washer is also likely to be higher, like abt usd220+ for 5800 at LNT n also 420+ at irobot for the 380 excluding shipping.
I currently own a roomba and believe I will still get a scooba later, cos' the 'sweep/vacuum' is really effective, to the extend the flr feels clean even wo mopping! haha .... I still try to manual mop with water once every 2 wks lah ...