I bought both, and sold both. What I like the most about the scangauge II with X-gauge is that since I have an Impala, I don't have to deal with the 3 pod gauge cluster which IMO looks out of place, like, well, we all know what the huge winged slow disposable cars look like.Oh yeah the price was about $90 less than the Aeroforce, and only needs connection to the OBDII port, no other power access needed. This gauge is also very handy for throwing in quickly for a quick monitoring.
The Aeroforce can scan more total parameters, has the additional input/outputs (connector your scanner, other sensors, WB etc.
Really two somewhat similar things you may buy for different reasons. IMO there is no right or wrong, it's a matter of what meets your needs.
My HPTuners is all I need.