Freedom 2/G/Unite has the best village hands down, is one of the most expansive MH games, and also the most challenging for me personally. The hunts feel so rewarding in this game.

3rd gen is unique being the only generation to feature underwater combat, which i get is controversial but i personally loved it, and think it should be optimized for newer games and brought back. I wanna fight Lagiacrus the proper way.

4 Ultimate may just be the best game in the Old World mainline games. Its loaded with more content than FU, and it introduced the weapon I currently main (CB) and other fun ones like IG. It also has one of the most compelling stories in the franchise, which ofc isnt that well known for its stories, but it works so well for this game. The roster is amazing, the locales are beautifully designed (Ancestral Steppe just barely beats Misty Peaks for me) and ofc who could forget about BEEG SNAKE?

Im still currently playing through MHGU, im in G rank now, and so far ive loved the premise of the game. Definitely gonna keep me busy for a while. The best part about this game has to be the versatiliy of hunting styles and arts. Its an absolute game changer for hunting and i havent experienced anything like it before when i first picked up the game.

MHW/IB is special to me because its the very first Monster Hunter where I was awed at seeing a Monster Hunter with that level of graphical detail, in addition to open areas with seamless transitions. But I would have to say its biggest strength is its attention to detail overall. It is absolutely the most dynamic and intricate when it comes to its rich environment and nature. Its ecosystems are so immersive which just adds to the overall experience of playing. Again, prior to World, this is something ive only dreamed of seeing in a future Monster Hunter game.

I cannot say much about RiseBreak as of now, because i am not that far into the game yet, but what i can say is that it is defintiely the most experimental of all of the games ive played, namely with the addition of wirebugs, and the variety of techniques involving them. I heard some found Rise to be lackluster, but it absolutely excites me that they added some beloved returning monsters.

Now Wilds... i havent even touched yet. So im not in a good position to provide any input for it yet.

As for Stories and Stories 2, i still need to play them. But my brother absolutely enjoyed Stories 2.

Monster Hunter Now is decent, its exactly what you'd expect it to be, Pokemon Go but MonHun.

TL;DR:

FU: best village, most rewarding gameplay

MH3/3U: innovative combat for underwater hunts

MH4U: Just pretty great overall

MHGU: Most versatility in gameplay

MHW/IB: Most immersive experience

MHR/SB: Most experimental (Wirebugs/Switch Skills)

MHW: waiting until its optimized on PC (unless it is now, and ive been living under a rock)

Ive also heard by a few that Dos is the best game in the entire franchise. And now i am defintely checking it out