I love weather 4d 2.0, I would love it even more if it was able to display my n2k data coming from my wifi network. Usually the options I see on ipad:
- weather4d 2.0 (navigation AND weather)
- inavx 
- predictwind

Garmin's Active Captain but you need a iPad 5 or a IPad Pro, some IPad mini's support the app. Also Navionics is a popular chartplotter app. 

Most folks find iPads hard to read in the sun, especially in waterproof cases.  A Bimini may help.  Have fun with the new boat

Unfortunately I can't recommend a good review of available units.  But I have been using iNavX on an iPad Mini 2 for the last 2 years and it has been flawless.  I bought a wifi-only iPad and a separate Dual Electronics XGPS150 GPS transceiver, which is a little GPS antenna about the size of a deck of cards that sits down below in the cabin and communicates with my iPad via bluetooth.  Very accurate and can easily communicate through the cabin top and other obstructions.  The iPad cost around $200 at the time, about $20 for a waterproof case, another $30 for an iPad clamp mount for the steering pedestal, and the GPS transceiver is about $80.  As for iNavX, you pay $30 or $40 for the app, but it uses NOAA electronic charts that are free and downloadable through the app.  I have not had any accuracy issues, system glitches, crashes, or anything, which is more than I can say for the super expensive chartplotters I have used in the past.  The only downside is the screen would be impossible to see in direct sunlight, as mentioned previously.  I have a bimini and have had no issues, but without the bimini direct sunlight would be a problem.  I would also recommend some means of charging while in use.  I installed USB ports at the instrument pod, so the iPad is always charging, but I imagine without it the battery wouldn't last more than 3 or 4 hours.