Alright. So, you're probably wondering:
"
Knight, why do you prefer the mid-end? The low end makes the safest assumptions, doesn't it?"
And yes, that would be true. That is, if the planet they jumped to was similar enough to Venus to be suspected of being Venus. However, this is not the case.
As seen in
this video, during the portion of the fight where Dante and Mundus are flying through the atmosphere of the planet they leap to, the storm clouds that surround them are dark gray.
Now, what color is Venus' atmosphere?
Distinctly not dark gray.
So, we cannot assume that the planet is Venus, as the planet's storm clouds are gray, whereas Venus' storm clouds are a sickly pale yellow, almost like coffee with too much cream.
So, since we know that it cannot be Earth (Earth isn't as volcanically active as the planet they landed on, obviously), and now we have to rule out Venus as well, because of the unmatched atmospheres.
Because of this, there is not a single planet or astronomical body within the Solar System that A. has the same level of volcanic ability, B. has a thick enough atmosphere to generate significant storm clouds, and C. has dark gray storm clouds.
Io, Titan, Venus, and Earth each have different traits of each planet listed, yet none of them share all three. Earth has the atmosphere and dark gray clouds, but lacks the volcanic activity. Venus has the atmosphere and volcanic activity, but not the cloud color. Io has the volcanic activity, but not the atmosphere, since it uh... doesn't have one (gasses that cling from volcanic eruptions don't count). And Titan has the atmosphere, but it's volcanic activity is with water ice instead of lava, and the color does not align.
So, we cannot reasonably assume that they have jumped to anything within the solar system, as each body that has one or more of the needed traits, also lacks one or more of those traits. Similarly, we cannot assume they have jumped to a rogue planet, because those are cold, dead, and calm planets with no volcanic activity what-so-ever. Additionally, most rogue planets are Gas Giants, not rocky planets like the one Dante and Mundus landed on.
So, our safest assumption, given what we have already assumed (bare minimum distance from the sun to appear as if they are in interstellar space), and that no planet in the solar system is a reliable candidate, we must assume they have traveled to another solar system, in which case, Proxima Centauri b is our safest option.