Which is the best GPS, FISH FINDER fpr a 2006 yamaha ?

it's really a subjective answer.. some guys like hummingbird because of the big buttons, others like Garmin because of the interface. at around $600-700, there really isn't much difference. so it's basically up to you to decide which screen/button/interface/size/etc. is more important to you. with that said, there are the mercedes and jauguars GPS/FF combos. for example, take a look at Lowrance and Raymarine. All the big boats use it because it's power and accuracy. but you pay nearly double the price!

my suggestion, besides feedback, make a trip down to your local marine store and play with the units. ask the sales rep questions. they sale these for a living so they'll know exactly which works well for your budget.

I have a Garmin 410c, fishfinder only.

What is the cheapest one that will still do the job?