Cloudkicker is pure genius. He blends metal with post-rock elements like Rosetta but with a more math metal style. Plus he released his music for free on bandcamp and only asks for donations if you like his stuff.
Russian Circles is another band that's been blending rock elements with post-rock for a while.
City of Ships is on the same label as Rosetta and they've toured quite a bit together, people who like Rosetta seem to enjoy City of Ships and vice versa although the two bands have some distinct differences in approach.
If you enjoy the atmospheric post-rock parts of Rosetta you might also enjoy instrumental band God is an Astronaut.
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No one, they are to unique to be similar.
There are many bands that are most similar to The Ramones! Actually, there is sub-genre of punk called "Ramonescore", Bands who has the same playing style as The Ramones. Bands Like the Queers, Screeching Weasel,Huntingtons etc.
snsd
I like Imagine Dragons a lot, and some other bands that are somewhat similar are X Ambassadors and Mumford & Sons.
Probably utauloids
My personal favorite is Madam X, but you can find all kind of bands similar to Nitro here:http://www.tastekid.com/ask?f=1&q=Nitro
Some of the similar bands would be:http://www.tastekid.com/ask?f=1&q=Bone+Thugs+N+Harmony
No bands are like katy is what i think because theres no two people alike. :)
The Smiths, The Stone Roses, The Beatles, The Who, Blur and basically all those good rock and roll bands and a few indie bands.
I've always considered Sevendust, Chevelle, and Rage to be similar.
Fireflight is very similar