Doubtful, the Prometheus class probably is.
The Sovereign class has 16 type-XII phasers and 10 torpedo launchers, one of them being a highly powerful quantum torpedo launcher on the front. It also is rather tough in battle. The Sovereign class is a cruiser, and the Prometheus class using multi-vector assault mode can divide into three warp capable sections, each with 6 phaser arrays and a torpedo launchcer, like a small fleet working together for the kill. Multi-vector assault mode doesn't always work in every situation, say a very risky battle, such as a Borg attack, which may require a strong capital ship than three small ships that the Borg could take on one at a time, in which a Sovereign class starship would be better at fighting, with more weapons and shield, in compairison to an assembled Prometheus class (sorry about the run on sentence). Prometheus class starships are faster and can cruise at warp 9.9 and in emergencies travel even faster. Acording to some sources, the Sovereign class was designed to travel at a maximum speed of warp 8, upgraded to travel at warp 9, warp 9.5-ish , after the refit by 2379, and warp 9.975 (or warp 9.985) after the 2385 refit. It is a toss-up in different situations.
Basically, the Prometheus is best when you need to be fast, maneuverable, and attacking several sides of the enemy's shielding, while the Sovereign class is best when you need a strong and deadly tank/ cruiser.
The Sovereign-class Enterprise and other Sovereign-class starships were obviously built because the Federation was collectively tired of being messed with. The class name was probably chosen to memorialize the class being a specific response to the collective threat by belligerents against the Federation's sovereignty over Federation space.
This state of affairs is recognized impliedly in dialogue, by Ahdar Ru'afo, in Star Trek: Insurrection, when Ru'afo observes to Admiral Dougherty "the scent of death on the Federation", and spoke of the Federation being "challenged by every power in the Quadrant" (as also the Dominion and the Borg have challenged the Federation). The Prometheus class (Prometheus was a figure in Greek mythology of pivotal importance to Humanity) was likely built to be strategically and tactically complementary to the Sovereign class in the fleet, given its differing flight and armament characteristics, in anticipation of an arms build-up (or in response to one) from the Romulans, and threats from other belligerents, too.
This fear proved to be well founded when Picard and the Enterprise-E command crew encountered the Reman Warbird Scimitar in Star Trek: Nemesis, although there are indications of a perestroikaesque movement within the Romulan Star Empire, subsequently, after Commander Donatra worked with the Enterprise-E to destroy the Scimitar. The Empire is unlikely to return to its old ways, after the Shinzon incident ProfessorTrek 10:23, August 19, 2011 (UTC)