I like this Odyssey-class Enterprise
-F. For the particular timeline it's set in (very early 25th-Century) it's contemporary to the starships that would likely still be in service during that time.
I think it's relationship to the Sovereign-class is not too unlike that between the Excelsior- and Ambassador-classes. Similar, but also different.
Comparison to the Enterprise
-E (warning: really huge photo):