I use an LG GPAD 8" tablet that has acceptable brightness. A lot depends on where you mount the tablet so that it doesn't reflect, on the glass, any bright object in the background.
I have used my tablet attached to my kneeboard and even with a cockpit that has plexy at the top I can still see it OK.
I have just changed the position within my Avid Flyer cockpit. I used a RAM mount to place the tablet just to the right of the center of the lower edge of the seat. I fly 99% of the time solo so it's not a passenger issue. Then I use my Android phone on my kneeboard. The phone is set to full-screen nav mode and the tablet is set to full-screen EFIS mode.
In both cases you do have to look down to see the presentations, however, I have the audio alerts on my headphone so that the alerts tell me to look down at the screen.
John M