I've been playing since the PS2 with the original Monster Hunter. Currently my favorite is MH: Freedom Unite for the PSP as I found it to be the most accessible while still retaining the awesome challenge level (once you reach G-Rank) of the original.
Can't wait for Tri Ultimate to come out. I haven't played a Monster Hunter game since the first PSP one (borrowing the PSP and game from a friend). Still my favorite series. Going to end up buying both 3DS and Wii U versions. =P
I have been playing Monster Hunter 3rd Portable on the ps3 (Japanese with english patch). I'm looking forward to the new MH with the option to jump on monsters and hacking them while you are clinging to their back.