I think the greater graphical flexibility means LEA will look much nicer than Powergrid IF you can take some extra time/talent to set it up. I think the example screenshots are a slight case of "programmer art" (no offense intended, if people involved are reading this). Once you get a designer in there, they can do more than in Powergrid, and I think the results will be suitably impressive.
I'm slammed with other projects at the moment, but I'm looking forward to someday having some time to do something slick with LEA and hopefully prove my theory.
Powergrid
has not been updated in over two years. To me that indicates it's abandoned - that means I should not expect it to get any of the fixes or updates I would like, not soon, not any time time in the foreseeable future. People posting new grids on a website means people still use it but it's not really the same thing.
That said, Powergrid is simpler, and it comes with lots of really nice art assets so I agree it is definitely quick and easy to get it looking really good. LEA is a newcomer (I think) and will take a bit more time to accumulate that quality of art assets, but to me it looks like a better foundation for the long term.
Another thing nice about powergrid is that it allows you to design the UI on the computer. Trying to arrange the UI directly on the tablet is more awkward IMHO because tablets are more awkward. Maybe LEA allows it? I should double check but I think with LEA at the moment you do it mostly on the tablet. Some people will like that. I don't.