A while back, the answer was simple - ATI HDTVWonder because that was the first ATSC device we supported. It is also by far the best I have tried.
Now there are more choices, many we have not tested. I am not even sure if ATI still sells ATI HDTVWonder. They probably have newer products. You can try one of them.
I just tried KWorld PlusTV HD Stick 330. It works, but not very well. The HDTV part works, but reception is not as good as my old ATI HDTVWonder - using the same antenna that came with the ATI device. The KWorld's portable antenna is much less powerful. The antenna is a big issue if you live far from the TV stations as I do (I am 25 miles from most stations, except one). I also noticed an issue with the analog portion of KWorld device. That however is easy to fix, and I will fix it soon.