Spoilers for the babies who haven't read book 3 yet:
Ramuthra would apparently win. Anyway, why does it matter? The matchup is impossible so comparing two things when you know about 1/20th of their power is asinine. We know barely nothing of Nouda and we know Ramuthra can warp the fabric of reality. Under the circumstances you'd say Ramuthra because the rift would most likely just absorb Nouda, but the rift was not Ramuthra's power as much as it was just the portal it came through. Nouda was also incredibly powerful and survived a full-on assault from the Staff(at least the controllable part of it), and on the other hand Ramuthra would have just diverted it.
I'd say Ramuthra because
a.) Nouda wouldn't be able to touch it with magic, for the spirit bent reality and all attacks disappeared.
b.) It couldn't get close enough for a melee assault without being considerably altered.
Gladstone/Sentynel/Krim/Gladstone/Sentynel/Krim/Stroud/Gladstone
The three ships. Kinda like the Mayflower and all those.