One of the challenges of 3D printing is model adherence to the build platform. Searching for this topic will return many, many, many results. Hours into a print and it pops off the platform can result in loud screams.
The only thing that I ever used with my Prusa I3 was glass. This may or may not have been helped by the fact that I only ever printed with PLA. In any case, it was glass with either ABS Goop or Hairspray to aid adhesion.
When I got my Duplicator 4S I started to play with ABS and ended up using FR-4 after finding reference to this stuff on the RepRap Forums. I have written about FR-4 here as I really liked it at the time and for a while. What I liked about it was how forgiving it was as a surface...you get good adhesion with a pretty wide range of platform leveling. I also like the fact that as it cools prints just pop off. What I decided that I did not like about it was that it was not a completely flat surface and that it seemed to be getting less flat with time! I was using pretty thin FR-4, and there is thicker stock available, but still.
One of the print tasks that had me frustrated with FR-4 was a job that required a high degree of detail on the first layer (lettering done with 0.5mm strokes). I found that I had difficulty getting this level of precision with the FR-4 so I got out the Klapton tape. I have written disparagingly about Klapton tape but it wasn't too bad. I have a roll the size of my platform and was able to get a new surface relatively easily. Print adherence was great. Here in lies the rub. It was too great and Klapton tape is too fragile and putting on new tape is a pain.
So, it was back to glass.