From reviewing the list of past monsters, I would also like to see the return of mammals Azuroth, Lagombi, Nargacuga, and Zinogre.
Even though the dual Tigrex quest in Monster Hunter Freedom Unite was the quest that almost prevented me from beating the game, I find that Tigrex is a must. That quest forced me to use the "noob-ish" lightning longsword
Interestingly, since beating the dual Tigrex quest, I found fighting a single Tigrex fun and not so challenging anymore.
Deviljho and Ludroth are also much wanted, and unlike most people who don't like water battles, I hope we have underwater battles with Ludroth, Lagiacrus, and so forth. After looking at the collection of monsters, I actually want almost all of them to be in MH:World since it does get tiring hunting yet another Rathalos and its variants. So a better question is which ones do we NOT want?
This is obviously subjective, but I wouldn't be sad if there's no Plesioth. I hate how it hides in
|Plesioth--still does damage from across the screen|
On the other hand, I'm hoping that MH:World includes all monsters of past series (even my most hated ones) for the variety to make it the biggest and best Monster Hunter!
Monster Hunter fans, which monsters do you want or not want to see?