There is NO one detector that can "do it all". I have 11 detectors and some dozen accessory coils.
PIs, single, dual and BBS frequency detectors. Each one combined with a coil is chosen for any given area / environmental conditions / anticipated target.
The closest go anywhere detector go anywhere detector I would have to say is the Excaibur with the 10 inch coil. If you plan on dirt digging then the 8 inch coil might have a slight advantage especially in a trashy area. The Excalibur has the advantages of its iron mask, multi-frequency BBS which allows salt and fresh water detecting, volume control, sensitivity control, "all metal" mode, auto ground balance. rechargeable battery pack, hip mountable are all pros, Cons: headphones and coils are not user interchangeable.
All detectors are electronic devices that see a lot of harsh use...in the water, wood, their cables pulled and stretched, their controls either pushed or turned, battery doors opened and closed, O-rings pinched, cleaned, and grease. With all this going on every detector is subject to the need for repair. I personally hold Garrett is high esteem in the realm of customer service. Now that Kellyco has taken on the repair of Minelab, I understand they are also great in handling repairs / modification of Excaliburs.
There are many posts with subject matter on specific detector and some comparisons. Use the SEARCH feature on the forum and you will probably find what you area looking for. Your local dealer would also be a great source of information.
Good luck in choosing your detector. You are on the edge of a great hobby. Enjoy every swing.