Hi kaingearoo
And welcome to the forums!
Out of the bikes you've chosen, the Hoo Koo E Koo probably has the longest history, and as you stated it comes with the genesis geometry.
I think I'd go for it when put against the Trek and Giant just on the strength of that alone.
Let us know what you go for...as you've probably seen, Mountain biking has developed somewhat since you last swung your leg over the saddle
Rich