I use a Garrett Ace 250 its a so called entry level machine but it does a great Job I would have to go several grades higher and into the big bucks to find a machine that would out perform it enough to warrant the extra investment. A word of warning though despite the adverts the machine is not switch on and go. To get the best out of it you have to spend some time getting to know it and adjusting it for the ground conditions you are using it on. It gets me out of the house three or four times a week when I am at home and it gives me exercise. Its also one of the few hobbies you can turn a profit on with a little research.