Gold is actually relatively hard to detect, unless it is a sizeable chunk. It does not give a strong response like a ferrous metal, it responds about the same as lead. So, you are much more likely to dig up a bullet, than a nugget.
For maximum sensitivity you need a metal detector that is relatively simplistic and that can be operated what I would call, "wide open". In other words, little or no discrimination. Detection of gold is also enhanced by metal detectors that use a slightly higher detection frequency (60 - 80 Khz), as opposed to relic hunting metal detectors that operate at a lower frequency (20-40 Khz).
I don't like hunting placers and deep alluvial plains for gold, digging deep holes. This is for the guys going after the nuggets. They utilize a special type of metal detector called a Pulse Induction (PI) detector to give them the depth. They are big, heavy, and very expensive.
I like going after in-situ gold in veins, or on dumps. For this, you want a lightweight metal detector that you can swing around underground for hours without wearing your arm out, that is able to get into tight places. My tool of choice for over 20 years, is the Fisher Gold Bug. The current model is the Gold Bug 2. I note that it has been improved since I bought mine with a simple little LCD display. Light, rugged, agile, reliable, tuned for gold (very sensitive), and very simple to operate.
I do some above ground prospecting, in areas with lots of gold diggings. For this, I like a detector that can also screen out trash if you want it to, and has good depth penetration. My favorite for this is the Minelab Equinox 800. It is a good, "fits every occasion" detector with a dedicated, wide-open gold discrimination mode. It is also very lightweight and rechargeable. I have found gold with it. There is more VG in Arizona than in Nevada. Nevada has a lot of disseminated Carlin deposits with micron gold.Tom's Bird Info / tom@mmto.org