For the 'shaky-cam' genre for me the best is Blair Witch(the source/origin of this genre) and Quarantine (or you can watch the spanish/original version 'Rec' )
Compared to both of these movies, paranormal activity is not as convincing.

My other recommendations: (US)

1. The Descent - Don't read the movie summary( coz it's sounds shallow) and just watch the movie. You'll be surprise how terrifying this movie is.
2. Sixth sense - If you have not watch this, may the ghosts in the movie haunt you.. haha just kidding, but seriously for your sake, watch this brilliant movie

Japanese
1. Ju-On 1 & 2 - I haven't watched both for a while already, but all I can remember is that I felt truly disturbed after watching both, and all I can remember is from the 2nd one (spoiler) is when they reveal the reason for the thumping wall noises *gasp*
2. One missed call - If you scoff at this suggestion because you saw the american remake and not the japanese original, then I pity you..coz you really should have watched the jap one first and not touch the US one at all

Hong Kong
1. The eye- A true classic ( Also, there is a US remake which you should also avoid at all costs) . This movie is not as scary as the rest but the story itself is awesome.

Thailand
1. Shutter - obviously
2. Alone - not as good as shutter but still good