Whatever you purchase make sure it actually has a built in GPS. Do not get just the cell tower position finding which will not work on most parts of our coast.
We went with a Nexus 7 tablet, 2 of them, and have found them terrific. Both have the Navionics.
I can park one directly in front of me which is a huge bonus.
We used and still have an older laptop which now has NOTHING on it but the chartware. But it was well off to one side so was not easily used by me.
The Nexii fixed that. My wife has hers, I have mine and the two give us redundancy if one fails.
There is a disadvantage with the small screens and that is the small screen. The laptop had a huge advantage that way but it has been overridden by better positioning, ease of use and uses a LOT less space which we are short of.
I suppose if we were on a long cruise to unfamiliar territory I would take the laptop as it still works well.