I say Monster hunter 3 ultimate. Its based on wii version which is most easiest to get into.
Monster hunter freedom unite is really difficult at first and then its manageable and after that it becomes hard again and finally you hit the wall, lol. Good thing is that its only 10 usd or euros. Its worth the money and you can warm up with it and learn the basics. If you do buy MHFU then USE HEADPHONES because its not too impressive with vita's speakers but it becomes really immersive game with game when you use headphones. Capcom made really good work with sounds on MHFU.
Ultimate plus a Circle Pad Pro will be the best of them. Without a Circle Pad Pro I'd recommend Freedom Unite digitally so you can use the Vita's analogue stick to control the camera.
You do not want to play without a second stick even if some people can do it using "the claw". --- JRPG fans, support our struggle: http://chn.ge/SsowWy Join our cause: https://www.facebook.com/OperationDemonBane
3U, and you don't need a cpp to play. People have played perfectly fine without it.
this, and not even using the claw, i had MonHun 3g since it came out on dec 2011 and played it for almost a whole year w/o getting bored of it or haveing trouble with control/camera, and MonHun 3g has everything p3rd has with the exception of a few monsters that were avaliable on MonHun 2nd g, or freedom united, depending on what country are you from, so if someone tells you that p3rd is better, slap them, i have 2ndg and p3rd on my vita and 3g on my 3ds. --- Screenshot it or it didnt happen.
Portable 3rd is the best to start with, but MHFU is the best content-wise and it's the most difficult as well.
The non-portable series of MH (MH3, MH3G, MH3U, etc.) turn me off for some reason. I much prefer MHFU and MHP3. Just my opinion though. --- Playing - Too much. But mostly Vita, PS3, and PC games. PSN: zandm7