There is no such thing as too much flow (non linear), well you couldn't develop enough probably. You may want to take a look at what type of fish you want to keep. Some fish are skittish when the flow is HI say seahorses (extreme low example). Some larger tangs and wrasses like the high flow. If you have any desire to someday keep SPS, anemone or something that like/require high flow rates you may consider that as well in your decision.
I ran a single Tunze 6100 on a controller on my 120 (48x24x24) and had it running 30%-90% surge. Did not have any fish hate it and my SPS loved it. With the 6100 you can throttle it down quite a bit if you don't want as much flow. I probably would not waste money on the Nano stream, not because they are not great pumps but for a 120 they are undersized.
Good luck
