Truly can't decide. Minelab, Garrett or Fisher.

I've got no experience with the f70.

The AT Pro looks pretty good. I'm pretty sure it's waterproof to 10ft so that's a cool feature.

I like my 70 very much. Unfortunately it's not waterproof, so I'm limited to only hunting on land.

Both the At Pro and 705 are great choices, but personally I'd got with the 705. It's got great overall depth, and I like how ferrous signals are appear as negative target ID's, and non-ferrous targets are positive. (and I know that's biased because I haven't got as much experience with the At Pro)

If hunting land is primary and water isn't a factor I would consider Tesoros. I'm not into the bell's and whistles and lcd screens and those machines have real lifetime warranties.

you keep mentioning water proof. if that's what you want, you already have the answer.