Its more so V to I cadence is the strongest not because its the farthest, because by the logic than the tritone would be the strongest. Its because of the overtone series and how the perfect fifth is the first note that is not the root, and therefore the ear hears it very readily.
Just want to clarify some points here (even if it's not exactly "practical gig" stuff, but a read through this may explain WHY ii-V-I in more terms than just "think of it as a modified 12 bar blues - which in itself isn't an explanation since 12 bar blues hasn't been explained).
The fifth is the first note in the overtone series (other than the root/octave) but that's not what makes the V-I satisfying.
For reasons I won't go into here, there's a school of thought that says all chord progressions are based on I, IV, V, and any other chords are just substitutes for one of those chords. This is simplifying things a bit, but this concept often works well in practice.
Out of I, IV, and V, the V is the one that contains the most dissonant notes.
I - root, third, fifth - all sound very good together, very closely related to the root, heck these note are all derived from the overtone series of the root and the chord itself IS the root - not very adventurous.
IV - fourth, sixth, root - this is practically an inverted I chord. Start at I, and go a (minor) third down, and a perfect fifth down and you get an IV chord. So nothing too adventurous going on here, all the notes here still work well with the root.
V - fifth, seventh, second - well the fifth comes out of the root, so by itself it isn't so exciting*, but the seventh & second are dissonant to the root and strongly want to resolve to it. Out of I, IV, V, this is the chord that has the most interesting stuff going on.
* Though technically all the notes in a V major chord are derived from the overtones of the note itself.
A ii can be thought of as a chord substitution for IV. It contains to notes in common with IV, which makes it a good chord substitution. It has the added benefit of being "the V of the V" (it's a fifth higher than V, so all the things we said about the V chord - well the ii chord does that to the V chord) so it leads nicely to the V, which leads nicely to the I.
Et voila - ii, V, I.
You can extend this out further - vi is the fifth of the ii, and iv is the fifth of vi, and we get to a chord progression I think a couple of people mentioned above:
iv, vi, ii, V, I.
* (or technically "the v of the V")
BTW - lowercase letters mean minor chords, CAPITAL letters mean major chords. We use roman numerals when referring to chords and numbers when referring to notes. (E.g. a V chord is made up of 5, 7, 9.) It's a habit you should get used to, you'll see it a lot, especially when reading a forum like this.