I like whiteboard, it was in my favs for a while. But i will always thing that monkey tower defense games are the best not contest. My friend found a Monkey towers 3 with 4 new levels, its prety fun here it is if you want to play it.
Well Some people like the "simplicity" i.e. you don't have to control masses of units and some people like it because unlike most RTS' it is not a rush you can take your time