Which 24-70? F2.8 mkI vs F4 IS?

Looking for a general purpose walk around zoom to fill out my lens line up and would like to stick with canon but the 24-70 II is just more then I want to spend right now so, the question is, if F2.8 isn't a must have but, a definite added plus would you rather have a used 24-70 mark I or for roughly the same price a refurbished 24-70 F4 IS with a canon one yr warranty? (The added weight/size of the mkI really doesn't matter to me. My main thing is the better IQ of the two.)

Every lens I buy from now on will be IS. I am in love with the three I have. Go for the f4.

i'd go for the tamron 24-70f2.8 VC before the f4...

DreDaze wrote in post #17100337
i'd go for the tamron 24-70f2.8 VC before the f4...

Me too, i will seriously consider this Tamron SP 24-70 f/2.8 VC which seems incredible ...
This lens receive the gold award from DPreview > http://www.dpreview.co​m …n/lenses/tamron​_24-70_2p8

I have heard great things about the Tamron, from people who have used it. Unfortunately I also know someone who got three defective copies in a row, so it does happen. I highly recommend buying from a shop with good buyer support and return policy; that's what I do.