Hi. Alot of people will come here and will recommend you the IBU 3, it is much popular.
Said that, If I were you I would buy the ASP 2. I had IBU and sold it to buy more ASPs. That says all.
Take a look here. WAY WAY WAY more options and sound quality than his competitors.
http://rctanksaustralia.com/guides/index.php?title=Asp2