We all have preferences on how we would like our boats to be set up, but there is some common ground that I find top level bass fishermen tend to gravitate to when it comes to what exactly they put on their boats.  I'll dive into what I think would be the absolute best marine electronics set up:

Ionic Lithium Batteries

Without proper power, too many electronics would be a liability.  Luckily, Ionic Lithium makes it easy to get a boat juiced up.  My favorite battery array includes three 12v 100Ah Ionic Lithium Batteries for my trolling motor.  I find that going with three 12v batteries rather than one or two 36v just makes things easier in case of emergencies.  36v chargers are more difficult to come by and if a battery were to fail, I could get by with replacing a lithium battery with a cheaper version temporarily.  I would then use a single 12v 125Ah Ionic lithium Battery as my cranking along with another identical 12v 125 as a dedicated electronics battery.  My tendency would be to run a forward facing sonar unit along with the box that runs it on the single dedicated electronics battery and run the other units on the cranking battery.  Many boats won't need that much power, but, for my favorite set up, we will be needing that extra juice.  To top off the battery side of things I would run a Minn Kota Precision MK-550 charger.  Rather than parallel charger the two 125Ah batteries I would prefer a 5 bank charger to charge each battery independently.  

Lowrance

My all around fishfinder choice is Lowrance.  I enjoy the ease of use, operating speed, mapping, and scanning sonars that Lowrance has.  This part is really just personal preference as Humminbird, Garmin, and Lowrance all share similar features and can be used as a replacement.  For my electronics at the console I only want a single 16" unit, a Lowrance HDS Pro 16.  Some people prefer two, but I feel as if a single large unit does the exact job I want it to do without having excess screens mounted at my console.  Of course this unit will be linked to another Lowrance mapping unit at the bow along with Active Imaging HD, a Point-1 GPS puck, and a Thru-Hull traditional sonar transducer to read my depth on plane.  The other Lowrance unit would be a bow mounted HDS Pro 12, primarily used for mapping but also equipped to read traditional sonar from the trolling motor.

Humminbird

Humminbird has a unique technology that most pros find extremely handy: MEGA 360.  Humminbird Mega 360 is essentially a bottom scanning radar externally mounted beside the trolling motor shaft.  With a constant scan of the bottom, an angler can easily see rocks, trees, BEDS, and even fish themselves cruising.  The big advantage of Mega 360 comes by finding features along the bottom while fishing, instead of having to idle the areas using scanning sonars.  I would certainly have a bow mounted 360 unit, a Humminbird Helix 12, on and rolling while I was fishing.  When used in tandem with forward facing sonar, Humminbird 360 is a phenomenal tool.

Garmin

To finish off the ultimate boat set up, a Garmin GPSMAP 1643 connected to LVS 34 Livescope is hard to beat.  Again, this can be exchanged for Lowrance Active Target or Humminbird Mega Live, but I personally prefer Garmin when it comes to their livescope.  The big 16" screen on the Garmin 1643 along with the crisp picture of LVS 34 makes 'scoping and staying on fish just plain easy.  

Minn Kota Ultrex Quest

When it comes to trolling motors, three good options come to mind: Lowrance Ghost, Garmin Force, and Minn Kota Ultres.  Once again, I personally prefer an Ultrex Quest.  The Quest is essentially a beefed up, quieter, and brushless verson of the original Ultrex and so far has been excellent.  

Power-Pole Blades

Whoever says they don't use Power-Poles flat out doesn't fish in any shallow water.  Incredibly useful, good ol' power poles are a must for me on any boat.  Using them makes me fish quieter and more efficiently, plain and simple.