Hammerhands vs Battleaxe with nether surviving the Warhammer.
3025 Dragon vs 3025 Zeus; while never written in the fluff, I always thought it was odd both mechs shared a similar weapons profiles (AC/5s, LRMs, Lasers) The Zeus has more firepower and armor but the Dragon has speed while both serve as proud symbols of their great house military power.
Centurion vs Dragon; same reasons as above.
3025 Commando vs Panther vs Valkyrie, above.