I just got a Asus ME102 (MeMO 10.1) tablet. It's very nice, but I only bought to to use as a phone (Skype with our world travelling daughter). It was a fair price @ $200 USD
Is it the best? I have no idea, but it will serve it's main purpose.
The accessories can cost almost as much as the tablet; 32 GB SDcard ($80), microfiber cloth to clean the screen ($10), conductive stylus ($15), portfolio cover ($50).
A quick trip to the $tore for a cloth and stylus ($2 total) and some good sales (32GB SDcard - $32, portfolio cover - $18) brought the expense down to 25% of the cost of the tablet.
total cost - $250 USD
You listed two 7" tablets and one 10" tablet... I think you'll be happier with a 10"
One thing I found out is that flash is not supported on Android any longer. HTML5 works fine, but other sites might still req flash for video. whs pointed me to the workaround for flash and I'm also trying to install VLC (Google play tells me that it's not available in my country - must be a location thing... I turned all of that stuff off!) I might have to just download the apk and tell the machine to allow non-standard installs (once I figure that out again).
I don't mind the on-screen keyboard on the 10" display - it drove me insane on a HTC G2 phone (even the tiny physical kb didn't help!)
What you want to use the device for will help determine the "best" machine.