Tactical Cubes: 138 (ref: STVOY "Unimatrix Zero")
Cubes: 1,184 (ref: STVOY "Unimatrix Zero")
Spheres: 878 (ref: STVOY "Unimatrix Zero")
Total ships available: 2,200
The following is a summary/theory of Borg fleet strength relative to the Federation:
If 1 Cube matches 40 Federation ships (ref STTNG "Best of Both Worlds"), then 1,322 Cubes is equivalent to 52,880 Federation starships.
If 1 Cube matches 300 Federation ships (ref ST:FC, based upon non-canon sources), then 1,322 cubes is equivalent to 396,600 Federation starships.
If 1 Sphere matches 18 Federation ships (ref ST:VOY "Endgame"), then 878 Spheres is equivalent to 15,804 Federation ships.
Lower limit fleet strength: equivalent to 68,684 Federation starships
Upper limit fleet strength: equivalent to 412,404 Federation starships
While viewing these numbers, one should also consider the following:
-It's assumed a Tactical cube is equivalent to a typical cube, despite apparently having a superior armored outer hull. There may be other types of tactical vessels with similar armor, such as Spheres, Probes, etc. However, that's based upon pure speculation.
-The numbers used here were gathered from Star Trek Voyager "Unimatrix Zero". They were stated by the Borg Queen when she was finding craft with "defective" drones. At no point were these numbers stated or determined to be upper limits or even large percentages of the entire Borg fleet. Higher numbered craft could easily be possible. These numbers have merely established absolute lower limits to the Borg fleet size, and should be considered as such.
-Other vessel types have not been mentioned here, such as the Borg "Scout"(ref STTNG "I, Borg"), "Probe"(ref STVOY "Dark Frontier) and "Diamond"(ref STVOY "Dark Frontier"). There also may be other types not yet observed. Given these ships are much smaller than their Borg cube counterparts, it's not unrealistic to assume such craft would be available in significantly higher numbers. Since a Borg "Probe" is relatively similar in power to a Federation Intrepid class starship, they shouldn't be dismissed either.
-The Borg have recently been engaged in a massive war with Species 8472, which by all accounts cost them significant manpower and ships. In one battle alone, they lost over 300 cubes. This may indicate much higher numbers for the Borg fleet once existed, but was severely depleted during this conflict. However, one could also interpret the 300 ships lost as a significant portion of a fleet of roughly 2,200 "high end" vessels, hence the Borg's apparent corcern about imminent defeat.
-When saying "1 Cube matches 40 Federation ships", this implies forty Federation ships has equal footing against a Cube. As seen in "Best of Both Worlds", this is clearly not the case. And as also seen in Star Trek: First Contact, a single Cube was able to plow through the best defenses the Federation could rally against it, despite the Federation having approximately six years to prepare for such an encounter. The Cube in First Contact was virtually in Earth orbit before it was destroyed. Furthermore, the Cube was facing a battle hardened Federation, which had been engaged in a long term war with the superpower known as the Dominion. At this point in time, it seems the Federation's fleet strength had increased significantly. More ships and heavier firepower, such as the Defiant, are evident and apparently available. Yet despite given significant time, seeming advances in firepower, increased available numbers of starships and battle experienced crews, the Federation was only able to heavily damage the outer hull of the Borg cube, while causing "fluxuations" in it's power grid. Their ability to destroy the Cube was only possible with a human individual who still had a residual connection to the hive mind, and was able to pinpoint exactly where to hit the cube, causing a chain reaction which resulted in the destruction of the Cube.
***
Well, I hope the information presented here is useful to both those who wish to see the Borg defeated(ie: "If you only knew the power of the Dark side..."), and to those who wish to see the Borg prevail against the Galactic Empire(ie: "Resistance if Futile...").
What are you objecting to?
