I go back a ways, but here are some that I'd rank.
1. SB VII - the win over Wash capped perfect season, team's first title.
2. SB VIII - Dolphins dominate Vikings for two straight
3. 1984 AFC Championship Game - Marino, offense score 48 vs. Steelers
4. 1981 AFC Championship Game - Dolphins shutout Jets (this was Shula's best coaching season IMO)
5. 1985 Monday Night Win over Chicago - stops Bears perfect streak
6. 1971 Christmas Day playoff win over KC, the longest game
7. 1972 AFC Championship Game - hard-fought win over Steelers (needed a fake punt by Seiple to help pull it out).
6. Playoff loss to San Diego - Fouts duels Strock, an all-time classic. The young up and coming Dolphins vs. the veteran Chargers.
7. Playoff loss to Raiders 28-26 - A heartbreaker as Miami was attempting to become the 1st team to win three straight. Team went a long way without Csonka, Kick and Warfield who went to the World Football League.
Off the top of my head, that's it. These wins really meant the most to the Dolphins IMO.