In my opinion, Ernie's cues will be a good investment for years to come, especially if you are considering a high end cue. That being said, however, Prewitt cues are clearly a cut above most and are very precisely constructed with superb finish. You will not be disappointed and the market for them is strong.
Playability is too subjective for me to pick a favorite...you must make up your own mind. Ginas tend to be a little more quiet hitting than the Prewitt cues I have experienced.
If I must choose, Ernie gets the nod, but in all honesty, both cuemakers are on my list. Either one would be a good choice.