sandy-shoes, your question is a bit like asking "what is the best motor vehicle that money can buy?" The answer would be: It depends on what you're going to use it for.
For example: If you want to reach 160 mph, perhaps you can consider a corvette. If you want to pull out tree stumps, perhaps you can consider a low-geared big pickup truck? If you want to go off-roading, perhaps you can consider a jeep or humvee? If you want gas economy, perhaps you can consider a mini-cooper?
So too is it for metal detecting: there's a myriad of targets a person might angle for, in a myriad of types soils, locations, junkiness levels, etc.. Some people angle for jewelry, others angle for deep silver coins in turf, others angle in nail-riddled ghost towns and urban demolition tearouts, others ply the nasty mineralized salt wet, etc... etc... etc....
so your question needs to be more refined.