I went through 2 of the CT Motomaster racing jacks, the kind Wu-Watt posted. They're utter rubbish.

Now I use this: http://www.princessauto.com/workshop...ile-floor-jack

Ok it's not cheap but it's super smooth and durable, and I don't treat it gently either. IIRC Sasha at SG has the same one that he's been using for about 2 years now.

 

I have this one but got it for around half the price (~100) a couple of years ago when it was on sale
http://www.princessauto.com/workshop...num-floor-jack

Random tip, put a hockey puck on it because the rubber on the head isn't the greatest.