there is no such thing as a 'perfect' metal detector.
I am now in my 53rd year of metal detecting.
Coin & Jewelry Hunting in urban settings, such as parks and grassy lawns, etc., also at salt water and fresh water beaches, is something I still enjoy doing as much as possible. However, I am a devoted Relic Hunter, and while I might find myself selecting a detector and coil to search wide-open plowed fields, pasture land, range land and similar sites that tend to have sparse targets that are well spaced, allowing me to attain more depth of detection, should there be any desired metal targets that I consider to be deeply positioned, the vast majority of my Relic Hunting is done at moderate to very dense levels of discarded junk, especially ferrous type trash.
I use detector models and coil choices that still provide me with very respectful depth on desired targets when conditions allow, but most of the time, due to the amount of discarded debris that causes good-target masking, 'depth' isn't really achievable. You want to have performance that helps unmask a good target in a cluttered of bad-target area. I have owned, and parted with, a lot of detectors over the past 5+ decades, always trying to find the best that is out there to establish a working detector battery that all can complement the others. It's also important to consider the search coil sizes and types as well as the detector settings to best achieve the maximum results you can for the site environment you are searching.
It is very difficult for any one of us to provide 'for sure' information to others that is guaranteed to satisfy other's wants and needs. You said you want to buy 3 really deep VLF detectors. Great, but don't forget that most detector models that feature one or more motion-based Discriminate search modes AND a traditional Threshold-based All Metal mode, will usually achieve their greatest depth-of-detection when using the conventional Threshold All Metal mode. Most people will read and respond based upon their opinions of favorite models used only in the Discriminate mode.
Also, you mentioned the following detectors you are looking at:
Nexus credo gold
White 6000 di pro sl
White 5900 di pro sl
Fisher f-75
Compass xp pro more
Nautilus IIb
Bounty hunter red baron
Minelab sovereign gt
Most of those listed are older and outdated by today's standard.
White's replaced the 5900 & 6000 Di Pro SL models almost twenty years ago with a smaller-size control housing to use a slide-in 8-AA battery try and increased the Sensitivity of that model, the 6000 Pro XL, over the former offerings. The 6000 Pro XL was unchanged except for the name, to XL Pro, about sixteen years ago. It has been almost thirty years, in late 1987, when Compass made the Scanner XP Pro which I helped introduce here in the USA as I was their Marketing Rep at the time. It was competitive, back then, but not today for all-purpose performance and to try and get better depth.
Most of the other models you listed I have owned and/or used, and while some play for some applications, not of them served my wants and needs or provided the depth I wanted, when I was hunting sparse-target locations where better depth is achievable. I would suggest you reconsider some of the models on your list and shop for one or more [size=small](since you want 3)[/size] that might be a better match for depth-of-detection. Just make sure you match the coil for the site environment as well, and that includes a smaller-to-medium sized coil. I can get very good depth in some challenging conditions with the smaller coils I use, yet the bigger coils can't handle the brush, rocks, rubble or trash density the smaller coils excel at.
For example, I understand the need to match a detector and coil to both handle dense trash as well as get improved depth in more open, less target-masking situations. Note my Regular-Use Detector Team below. I get very decent depth-of-detection with my Nokta FORS Relic and FORS CoRe models, but out of my Target ID devices, the new Nokta Impact can match or better them in most search applications. I hunt trashier places most often so I rely on smaller-than-stock search coils, but haave them equipped as such:
Nokta Impact w/4X7¾ DD mounted. I need to get a lower rod for quick coil exchanges for my standard 7X11 DD.
A Nokta FORS Relic w/5½" DD. Another FORS Relic w/5½X10 Concentric, and my relic R-P FORS Relic has the standard 7X11 DD attached.
My main-use Nokta FORS CoRe has the small 'OOR' [size=small]('Out-of-Round')[/size] 4.[size=small]7[/size]X5.[size=small]2[/size] DD coil mounted, and my 2nd FORS CoRe keep the standard 7X11 DD coil mounted and ready-for-use.
Just my opinions of what works for me in my applications and I know some others will share their opinions as well. I also get good performance from my Regular-Use, not TID Tesoro models, and my Vaquero can hold its own quite well with the new 8X11 RDS DD coil.
Monte
