Only advice I can offer is read the threads herein and then buy the one you think you'd be happiest living with daily, once you've seen them locally.
Read, read, read, and then read some more - that way you'll be clued up and the decision you make will be the best one for you.
It's your money you're spending, so the only person who can convince you it's the right one to go for, is yourself.
Remember the 4270 is a single HDMI and other limited features, whereas the PX70 is twin HDMI, and the 427 is more on a par with it connectivity wise.
If it's likely to be a long term buy, then you want to be as best equipped with what you may buy and use with it in 12, 24, or even 36 months time.
If you figure you'll have it 18 months then change, then spend the least now as it'll owe you less when you sell it on.