Just a real quick run-through and I'm not messing with the +'s and -'s.
Godzilla=C (nothing really stands out as being unique about this design and the jaws are much too narrow)
Angilas=C (although it was very nice to see one of my all-time fave kaiju FINALLY make a return...after 30 LONG years...the suit design just didn't do it for me, there's just something about the head and eyes that bugged me and I'm not too sure how feel about the whole "rolling attack" thing either)
Mothra=A (only because Mothra's design never really changes all that much and has always pretty much remained the same, so the GFW design scores as high as it does only by some kind of a default not because it really EARNED an "A"...if the larva form is included in GFW, I can't remember for sure the A is a little more "legit" since that form always left me with the impression that it was "truly" a monster and not just some big caterpillar)
Rodan=A (Now here's a GFW design that gets an "A" and truly does deserve it...AWESOME design all the way around, better than any of the Showa designs including the '56 one and much better than the Heisei "puppet" Rodan, I just wish that Rodan had been utilized more in GFW thereby putting such a WONDERFUL design to proper use)
Kaizer Ghidorah=C (Overall, not really a bad design per se, I just would've preferred an appearance from King Ghidorah as opposed to Kaizer, but the new variation of the kaiju did serve a purpose as far as keeping the film somewhat fresh and interesting goes)
Ebirah=A (I'm giving this design such a high rating for the same reason I gave the Mothra design the same rating...there's really nothing that special about it but they didn't ruin it, so, again, an "A" by default)
Minya=D (I've never really thought there was anything special about Minya's look in the Showa films and the GFW design really doesn't do anything to try and improve it all that much)
Gimantis=A (Again, as with Mothra and Ebirah, merely an "A" by default)
Spiga=A (And this time...as opposed to the other giant invertebrate monsters included in this list...not simply an "A" by default. There was always something I liked about Spiga's design in the Showa films because even though he was a giant spider he didn't just look like a giant spider, there was something about his design that actually made him look like kaiju and not just a big "bug", and the blue highlights in the GFW design only add to the monster's cool look!)
Manda=B (The design for the kaiju in GFW is a nice one overall, but the CGI version of the monster is far too cartoony for me)
Hedorah=B (The monster I was looking forward to seeing make a return to the G series second only to Angilas was Hedorah and even though I like the '71 design better than the GFW one, the GFW one really isn't a bad one, I just wish it would've gotten more than 30 seconds of screentime

)
Gigan=B (Of all the new kaiju designs done for GFW, Gigan is probably the most ambitious one of the bunch and even though it is a very nice attempt, the original '70s design for the monster is still my fave of the 2)
King Seesar=C (again, another kaiju that I was really looking forward to seeing return to the series but there's just something about the newly designed face that doesn't quite do it for me and it's just too painfully obvious that there's a man in the new suit...the '74 design is BY FAR the better of the 2!)
Monster X=B (A really cool idea and a promising design for the film's only TRULY original kaiju, the real problem here is one that the GFW King Seesar design suffers from as well, it's just too obvious that there's a human inside it the suit)
and last and certainly LEAST...
GINO=F (there's abslolutely nothing special or endearing about the GINO of the '98 film, and the CGI FX for the giant iguana were far more realistic looking in the '98 movie than they are in GFW)