Neither of those lenses are good for portraits. A good allrounder would be to upgrade your kit lens to a fixed aperture Canon 17-55 F/2.8 IS USM (or tamron/sigma 18-50mm 2.8).
And then for portraits get the 85mm 1.8 or 85mm 1.2L if you can afford it.
But if you are up to upgrading to a L lens that can be used when you upgrade to FF, then 24-70 F2.8L would be a good upgrade. And at 70mm 2.8 you can make some good portraits, too.