I'm going try to avoid the word stronger and put it this way:
All things being equal, Domicile is more comfortable and familiar for a planet to be in than is Exaltation.
But things are never really equal, are they?
To use my own chart as an example (in my profile), I have two planets in Domicile and one in Exaltation - Jupiter in Sagittarius, Saturn in Capricorn, and Mars in Capricorn (for the moment, let's leave out that Mars is also in his Term).
My chart is a Nocturnal chart - with the Sun well below the Horizon. Therefore, both Jupiter and Saturn are out of Sect, whilst Mars in Sect.
Jupiter is Cadent, in the 12th House and at the Bendings (square the Nodal axis). The only aspect he receives is an applying sextile from the Sun.
Saturn is angular, conjunct the Ascendant within a degree, and makes or recieves no applying aspects by Moiety of Orb. Venus is separating from him, also on Capricorn. By sign, he receives a trine from the Moon, the presumptive Sect Lord in Hayz (there may be some debate about the Moon's qualification as Sect Lord due to her house placement - 8th House in Regiomontanus and 9th in Whole Sign since I use a hybrid of both).
Mars is in Sect, Angular, and is applied to by Venus. Being in Term, he also picks up 2 extra points of Essential Dignity using Lilly's point system - pushing him one point ahead of Saturn.
But wait, Jupiter is not only in Domicile, but also Triplicity - in Fire in a Nocturnal chart. This gives him more Essential Dignity point than either Saturn or Mars.
Depending on the situation, I can be Jovial, Saturnine, or Martial - but which is stronger?
Strength is not really a consideration - it's a question of quality. According to purely Hellenistic (and likely most Medieval systems) Mars would be the planet that operates most freely and effectively.
Each planet takes its own place in each chart - supported by the relationships it has with Essential and Accidental dignities and debilities, dispositorships and aspects.