I'd agree with most of the comments above but will add:
Mills: As with everything, it is "horses for coarses", having used the Woodmizer and Lumbermate they both have their own pros and cons. The Woodmizer I would say is more robust and a faster saw which is easier to use especially if you have hydraulics. If you are getting warped boards off a Woodmizer, you've not set it up properly. Spend another 1/2 hour at the beginning of the day setting up and sorting out the jacks etc and you'll have no problem.
The Lumbermate is a good piece of kit but I found it harder work and the setup time was greatly increased compared to the Woodmizer. It is a lot lighter and more nimble to move about, there's no denying the Woodmizer is a bit of a beast!
Woodmizer get a bashing as they are the narrow band mill that most people know but they have a lot of experience in the field and there are a lot of machines out there because they do what they're supposed to!
Hydraulics: They might cost more but for good reason, you are totally self contained so you can turn up on site and don't have to go back to get another machine to move the logs. Also you won't have the overheads of running and moving another machine. It will be interesting to see if tommer9's opinion changes when he's still trying to mill at the age of 65! (no offence tommer9, you Cornish are a hardy bunch!)
Forklifts: They're great in a concrete yard on a flat surface and you'll put the logs where you want them with ease. Go anywhere near gravel or a slope and you're stuffed! Unless you are only going to use it in a concrete yard, stick to your idea of a JCB type thing.
At the end of the day, every machine will have it's own problems that won't suit a particular days work but yo'll find a work around; we all do!
Good luck!