On my Onex I think the alternative for me is the Revmaster 2300 or the Sauer 2400. With the Revmaster I have seen lots of talk about how good it is, but I've seen no hard data in any airframe. The Sauer I know is much more Powerful than the AeroVee. The S 2400 UL weighs about the same as an Aerovee, but has 100 HP (90 at 3000 rpm). The S 2200 UL is probably too light, just a bit more than the Jabiru 2200.
Here you can see the Sauer 2200 UL in action on a warm summer day in a Trial weighing about the same as a Sonex (it has a magneto and a Sauer electronic ignition, so it can be hand propped).