I can get a good deal on the F19ltd but just not sure which one I want. I hunt fields where old houses once sat. I'm in Indiana so mineralization isn't an issue
F75ltd IMO. Has more features, better all around detector. Obviously more expensive but worth it. The display gives more info than the other 2, also has a nice backlight that uses very little power. The other two are great detectors also, but if moneys not an object you minds well get the F75.
I run the 6in elliptical on my F75, it's a great coil as well. I found 3 silvers in a pounded yard with it, but you'll be getting a 5in if you get the LTD so it's probably not worth getting a 6in as well, I'd look into the 15in coil, or maybe one of the other large aftermarket coils for field hunting.
I will say I've had little coils for every detector I've owned,and none could even come close to the f75ltd 5 inch.Now,I've owned one other machine where the bigger coil was a tad better than the f75ltd, but it's a good machine.