Bike porn

My opinion is:
Single speed is a no no on an MTB. It's just plain silly for off road. You need gears. Sorry.
29" wheels are a bit of a moot point but, personally, at the moment, 29" is not porn.
Aluminium is definitely out. Not porn at all. Steel, titanium or well engineered carbon it must be.
Correct geometry is a must, as is frame size. Any hard-tail with a seatpost with more than 330mm exposed is basically too small for the rider and not porn. Long stems can >>>> too.
Then it's just decent suspension forks, hydraulic disk brakes that aren't shit and top of the range componentry, of which there are many examples.
That's about it. Thanks for asking.

I think you have just proved you haven't got a clue (with every point you have made)