I would probably update that these days. GU is still cool but its got a shitload of problems, and it's been ages since I played 4U so I don't really have a formed opinion on it anymore. GU has some absolutely superb fights (Valstrax and a bunch of the Deviants) but also is really imbalanced and the progression is kinda lame. Still a good game, and a lot of the styles/arts are really cool if you're into that, but not as solid as FU IMO.
Ideas are good (return to grounded aesthetic, no load zones) but execution is horrid. Animations have been smoothed/blended almost everywhere which takes away from the snappy, precise feeling of old MH. Campaign is AAA hellscape of annoying characters and unskippable (without PC mod) cutscenes.
Difficulty curve is atrociously easy in base game. Monster AI is really random, head turns are long gone and instacharges even more so. You can now sprint while drinking potions, and can roll to cancel out of them, so you are basically completely uncommitted, and max potions now have one of the fastest item animation speeds in the game. At camp you can refill your item pouch at anytime, which breaks a ton of game systems and forced them to add strict time limits for the last few monsters, so people would actually have a chance of failing out.
Maps are crazy annoying and filled with slopes, ledges, cliffs, and cramped terrain, but unlike FU you can't reliably control the monster's movement so you're kinda SOL unless you use dung bombs to make it leave a bad spot. Monsters besides the quest target (which are present almost always) will run into your zone, roar to stun you, the target monster roars, the invader roars, and then they'll often just leave, which gets really old.
Tons of weapons got trashed IMO. GS now has a ton of its damage in this triple charge slash thing that needs way too much setup, so you can only really use it during a trip or get lucky by randomly throwing one out. LS is now focused on hitting generous iframe windows to give you full meter + great movement + long invincibility, and then dumping the meter with this janky jump move. Bowguns are now a shitty 3rd person shooter (even more than they already were lol), and item restock completely breaks the ammo system. Iceborne expansion's bad mechanic (clutch claw) was retroactively applied to base game unless you mod it out on PC.
As you can see I'm a bit bitter, I have to add a ton of restrictions for it to even feel like an actual MH game. And Tai probably hates it even more than I do lmao. Again though, it might be worth picking up on sale (or acquiring on the high seas) to see if you like the style, it's definitely more "reactive" if that's your thing and plenty of people find it fun.
>G rank stuff
Oof, 39 min narga is rough. Copper blangonga LS is really strong, definitely a great option once you get there. The G rank ore weapons (like Punisher GS) are a good option for early G rank, especially with good-old broken Sharpness+1. HBG sounds good for those three, Blos is also plenty doable with melee if need be, once you learn the dig setup.