Hello and welcome, buy the newest model you can afford, their were lots of upgrades done along the way!!
That being said, their are guys on here with over 100,000miles on their bike, so reliability is spotty on the earlier models. For the most part this is a well engineered bike that is over built to handle the power it can put out, and as large as she is they handle great! This monster will rip the handle bars out of you hands, so be careful on a rest ride. Good luck with you guest!!!