I have been doing lots of research like yourself...tons and tons of reading. Broadband absorption is probably the safest bet...unless you are aiming at a particular issue. As Bulldogger points out, there is a risk to make a room worse sounding if you go for something that absorbs mainly in one region. Products that absorb in one region are generally meant to be used to tackle a specific problem or to be used in conjunction with other products. (For example tube traps can be very specific in their absorption)
From my research, foam can be excellent too....especially the Auralex LENRD traps as Stevecham reports (others mail order foams may not be as good...be warned!)....but you will probably need more foam than fibreglass treatments to achieve the same impact. Dow Corning 703 or 705 fibre has higher density (roughly double) than foam and this gives it an edge in the LF absorption per unit of treatment. Realtraps web pages is another good resource to read up on.
Placement is another crucial factor. You can "tune" to a certain extent using the quarter wavelength rule in distance away from a wall (often this is impractical in most domestic settings) If you can't tune by going far from a wall then placement a couple of inches away helps and straddling corners works good too.
I have ordered four of the new type GIK triangular corner traps - so I'll let know my findings when I set 'em up. I believe this is a bare minimum of treatment in order to have some small impact. In theory they should work quite well but I have not seen many reviews, as the triangular versions are new. I liked their prices, which is probably why I took the leap. I won't lose much if they dont work well in my particular room setting.
For the moment, what I am telling you is all based on extensive research and thats it....and we all know the value of first hand experience - so take my comments for what they are worth...two cents!
G'luck and thanks to let us know how many you installed, where they were added, and what was the impact.