I have a 3 speed hub in a hilly area and regret not getting more speeds. At first, I had a short, flat commute of about 3 miles roundtrip and 3 speeds was easy for that. In fact, it was a little too easy so I had the rear cog replaced to get better gearing on flat areas.
Then I started going on longer trips with more climbs. Also, my commute went from 3 miles roundtrip to about 25. I'd think carefully about the type of commute you are doing. A few small hills or even just one big one on a 30 minute commute would not faze me on a 3 speed. But with an hour-long commute one way and several hills, 3 speeds may give you more of a workout than you want and/or put some stress on your knees. Some days I just walk up one of the steeper hills.