I got two waterbuck my first time out, common and DeFassa. The don't appear to be herd animals and they don't frequent open plains, so they may be easier to stalk than wildebeest, for example. Mine were, anyway.

Both mine were solitary bulls. They take a lot of killing and I was told the meat was impossible to eat because of the fat, which solidifies as soon as it starts to cool. The local staff were happy to get them, however.