I just added ABC Tap to the Corona Showcase. Both ABC Tap and 123 Tap were built with Corona SDK. I initially used libgdx to build the first version of ABC Tap but I got frustrated with the fragmentation issues on Android after I released it. Corona SDK has been smooth so far. I haven't had any complaints from Android users. That is saying lots because there are 800+ Android devices that you can target on the Google Play store.