I figured I was probably the only one!
To me, the Xindi reptilian ships are quite striking, especially with the use of purple colour not normally seen on starships. They are also aggressive but elegant exteriors.
The aquatic ships to me are quite lovely and I especially like the sense of them being filled with water, quite a unique image (although we never truly get to see this, I can imagine!). This makes them feel very different to most ships and also I enjoy the 'flowing' look of the exterior that mirrors the aquatic theme.
Then the Xindi insectoid ships - again these mirror the insectoid nature in design quite cleverly and I feel like they really do stand out, shape-wise.
To each their own, but I just couldn't help being really impressed by these.