Having recently tested a lot this method, I've finally determine my "easy and cheap" way to build PCB using toner transfer method. I tried a lot of things, different papers. I've also tested the professional photoengraving  method, this one can be considered for the most accurate (but certainly not the cheapest).

So, what's the recipe ? This is closed to the last one, but now way faster, since only ~ 10 minutes are needed. Main difference is you don't have to be careful while peel off the paper, toner really sticks firmly, there's no risk damaging the tracks.

• I use glossy photo paper for laser printer (135g/m²)

• wash your PCB board with soap, then with window cleaner (or detergent with alcohol).
• sandpaper your board with ultra thin paper (600, one used for body car)
• wash again the board with soap, then with window cleaner. It must absolutely be dry.
  
• preheat the board,
  
• place the paper on the board. Be careful, it'll instantly stick to the board.
• iron the paper., first smoothly to help paper to sitck firmly, then with a lot of pressure (~1min)
  
• continue with the iron tip, and redraw all the circuit (black tracks will appear through the paper), for ~4/5min.
• Ironing time: ~4/5min
• then place the board on hot water, no soap. Wait for ~ 3/4 minutes, watching the paper beeing soaked. 
• peel-off the paper. Most can easily be removed, only the last layer, where the toner sticks, will mostly remain on the board.
• peel-off again the paper with a toothbrush.  Don't hesitate, it won't damage your PCB.
• once done, dry the board. Check if you've missed some paper.
• clean the board with window cleaner. While it won't remove toner, it'll help to remove paper residue and get an accurate board.
• you're done. You'll then need to etch the board. Once done, remove the toner using acetone (nail polish remover works well)

This video shows the whole recipe:




Now, as a conclusion, here's a comparison of different PCB creation techniques:

	Photoengraving	Toner transfer with transparency	Toner transfer with photo inkjet paper	Toner transfer with photo laser paper
Ease
Repeatable
Accuracy
Fast
Cheap
Total