I think a lot of the time that a seal is leaking its usually just something holding the lip open a tad or damage to the lower tube itself which is allowing oil past/has cut the seal edge.
The SKF are bloody expensive, but do have reduced stiction and wear well. Is it worth it to you? Maybe.. maybe not. A lot of tuners opt to use them.
I find the OEM KYB seals to be priced more reasonably, offer good lifespan, and while they're not as slippy, they're not bad either.
The cheaper brands often have loads of stiction, offer 2-3 sealing lips, and while this can be a good thing in that they seem to never leak, they have so much drag that its very noticable.