Trolley if your going to be using it a bit.
I had a el cheapo from supercrap give way on me whilst under a AU, and it was a 2.5tonne jack.
My advice is go for anything not made in China. Armstrong or Ajax are awesome. It ended up that after the return of the supercrap (which it turned out was a recall, thanks for telling me

) I had enough for a Aussie made Armstrong.
Oh and a lession..
ALWAYS ALWAYS USE CHASSIS STANDS.