Ok Fresh water lakes.
mid priced machines. Garrett AT Pro, Fisher 1280X, Tesoro Tigershark, Whites BHID
A bit more expensive Fisher CZ-20 or CZ-21, Minelab Excab
Most expensive Minelab CTX3030
If you buy any machine below mid priced they are probably from China and not worth the powder to blow them up.
I used a Fisher 1280X for a long time and its a great machine. I now use a Fisher CZ-20 and a CZ-21. I have a friend that uses a Tesoro StingRay 2 which is not made anymore but the Tigershark is. Deadly on gold chains and small gold earrings.
I love my Fishers but I am very impressed with the Tesoro's.
I also have a friend with a Whites BHID and a friend with a Minelab Excal. Both great machines also. I haven't found a target yet they couldn't see and vice versa. I hunt with my friends exclusively in fresh water.
The key to ANY unit is to use it and get to know it. I have gone out plenty of times without finding gold. And I have gone out plenty of times and have found over a grand a day.
Keep in mind that if your wading you need a scoop, waders or a wetsuit if the water gets cold where you are and some people like a floating sifter.
I use my CZ-21 with a 10.5 inch coil probably 95% of the time. I hip mount it and find it easy to swing all day. I also dive. You didn't say if your diving or wading and I assumed wading.
Hope this helps.