Ive owned most brands over the years but for the last 7 years stuck with Lowrance simply because they work extremely well and have very good customer service if ever you need to ask a question. Garmin lost me with two faulty units and poor service that took over 12 months to resolve.
Firstly I believe navionics to be the best charts and most regularly updated worldwide, to get an idea on how the gold charts look which contain less detail than platinum take a look on this site which you can see chart detail anywhere in the world for free (just zoom in anywhere)
Navionics.
Back to the head units (lowrance). The only way to get more detail is by having the most resolution you can in the screen, this normally comes at a higher price for the more res.
I fish and dive so high down res is quite important as this gives more detail of structure and fish. Side res is also important if you decide to use a sidescan transducer or 3D.
With the above in mind the bigger the screen with the most res the more detail you are going to see which is why I opted for a 12inch Lowrance over the slightly lower res 12in simrad.
Some of my bottom fishing is in quite deep water 500m + and though Ive owned airmar tm 260 transducers I personally have found them to be a complete waste of money and quite finicky in deep water.
The standard 200/50khz lowrance transducer and the lowrance sidescan transducer will do everything I want. I can sound bottom bellow 500m and scan clearly 800m each side of my boat. The sidescan is also handy offshore as I scan out to the sides of my boat for bait fish, it even picks up krill.
Heres a few screen shots, some from an old hds gen 2 and some from my latest gen 3. Just to add you dont have to use them as a touch screen as theres an easy option to use the buttons instead, saying that I love the touch screen.
Jon
40kmh and still holding bottom with 200khz in 250m of water.
50htz heading deeper 500+
Shallow wreck
Krill
overlaying sidescan onto map + down sonar
As you can see sidescan is great for finding new dive sites and understanding the lay of the land before you get in.