Ok, putting my "factory authorized service centre" hat back on. The shop I used to run was a warranty depot for every major brand except Bosch.
Milwaukee takes the cake. 5-year warranty and a damn tough tool.
The "sawzall" is the homeowner grade unit. Plenty tough and reasonably unbreakable.
The "Super Sawzall" is the pro unit, has a reciprocating counterweight to reduce vibration to near nil and only breaks through neglect.
The Sawzalls use an orbital bearing system instead of a gear with an eccentric and connecting rod. It's stronger, period.
The OLD De-Walt recip used an orbit bearing but it has been discontinued and replaced by a cheaper geared eccentric system.
Hitachi is next with a 5 year warranty but the tools aren't as tough.
Makita, De-Walt and Bosch are all about the same level of toughness with 1-year, three-year and one-year warranties respectively.
Next are the "hang it on a wall so my friends know that I own tools" brands like Ridgid, Ryobi, Porter cable (Sorry, they're junk, you must have a very good one or take good care of it), Skil and Black and Decker.
BTW, If you're shopping, here's who owns who:
TTI tool group = Milwaukee, Ridgid, Ryobi
Stanley = De-Walt, Porter-Cable, Delta, Black and Decker
Bosch = Bosch, Skil and Dremel
Makita = Makita
Hitachi = Hitachi
Shawn