List your likes about Millennium era, one taking place from 1999-2004. Here are mine:
Godzilla and monsters in general are all mobile, unlike in the previous era.
Redesigns. G2K, GXM and Kiryu Saga Godzillas all have edgy, spiky appearance with adds a special charm to them, as opposed to Heisei's chonky look and Showa's little anorectic one. Despite being overused in this series, Mothra in both designs look like an actual living thing and not like over-colored stuffed toy, and her GMK's look is how she honestly should have looked in Battle for Earth, fitting Battra's hornet-like appearance. GMK Ghidorah is simply perfect design for KG, bearing all features I'd like for Ghidorah to have: theropod-like legs with bird-like feet, wings shaped akin to Showa Ghidorah's concept art, golden and visible scales, crescents on each of heads, wrinkled face and pair of fangs. Mechagodzilla became badass hybrid between Eva-01 and himself, enough said. I actually don't mind King Caesar's design from Final Wars. Anguirus' redesign easily tops Showa one. Gigan is the only one to look just too edgy and skinny for my tastes.
New monsters. They're common feature shared by all Godzilla eras. Orga's concept is unique among other monsters, actually looking alien and mutated. While his early concept arts looked like what Godzilla was intended to look like, that is whale-gorilla hybrid, it later evolved to something new and original. Megaguirus is nice change from immobile beam-spammers Heisei era feed us with, and her design looks beautifully edgy. Monster X, eh, he looks like Xenomorph with Doomsday's bone protrusions. Sadly new monsters were extremely rare in this era, as it was mostly just an old ones' return.
Special effects. For me, Millennium era is Toho's prime when it comes to special effects. Perfect blend between suits, miniatures and CGI, although the latter looks kinda bad compared to Reiwa's. There's not actually much to say here: wings move more fluently and naturally, monsters mostly move slowly but are capable of some acrobatics there and there, we even have underwater battles! And color palette doesn't look here too dull or too bright like in the MonsterVerse.
Soundtrack. Millennium era has absolutely fantastic score, featuring themes like The Feared God, Godzilla's Rage or King of The Monsters. It might sound controversial, but it easily matches or surpasses Akira Ifukube's, and the whole fact it isn't overused as much as they were in Heisei era really... you know.
Roars. Millennium Godzilla's roars are among one of the best Monster King's roars, rivaled only by Godzilla 1984-1991's and Godzilla Earth's. Ghidorah's roar is a nice remix of a classic bidibidi, while also giving it BVS Steppenwolf-sque feel. Baragon has finally after 36 years got his own roar, although it sounds a bit like Hedorah's roars.
Lack of continuity. Instead of being tight and consistent like Heisei, or inconsistent like MonsterVerse, Millennium era is an era of Elseworld, standalone stories. While constant returning to 1954 and not really giving Godzilla any new abilities is a bit underwhelming, it allows for much more creativity when it comes to an events.
