I can't say it's the best because I've never really tried anything else, but it works well for me...
On two tenders now I've installed Furuno's low end multi function device. Not the TZ product, but in one case the GP-1670, and the more recently a GP-1971. They are remarkably affordable, have build in fish finder capability if you add a transducer, chart using C-map chart cards, and have a built-in GPS. They will even plot AIS targets if you are so equipped.
In both cases I used a transom mounted transducer, I think a P-66. A C-map chart card can typically be found that will cover your cruising area for around $300. Using the current models, the 7" GP-1871 is under $700, and the larger GP-1971 is under $1000.
Oh, I also mounted a fixed VHF. Got tired of forgetting the handheld, or having to fumble around with it. VHFs are really inexpensive, so I just went with it.
I think the biggest challenge is space for everything. On my last tender I mounted the plotter in a pod which may have cost more then the plotter. This time around I'm mounting in the tender console. It looks like it will fit - fingers crossed.