I going to buy one just wanted some opinions on which one to get I hope to be able to use it with my yamaha wind controller
No way to compare: AFAIK gigaviolin is not out yet. I have heard positive things said about it recently, and to me that means it must be good, as Garritan's Strad certainly raised the bar very high. I am looking foreward to hearing what Tascam brings to the table with this instrument.
GigaViolin=Promising, but thus far rather mysterious.
Conclusion: If you've got the time, wait and see. My understanding is that Tascam is just waiting on manufacture/printing.