For reliability I would have to say Simplicity, I have had many snowthrowers and tractors made by Simplicity (maybe because I'm a Simplicity garden tractor collector/restorer). And I have had GREAT service at any Simplicity dealership I have gone to.
You might want to check out this other Simplicity Garden Tractor Club on the web. I've been a member for about 5 years, been a past Treasurer and now just enjoy being one of the 3900 members. Oh well too much of the my opinion can go a long way on these yard machines.
http://www.simpletractors.com/club2/active.asp
http://www.simpletractors.com/default.htm