Overall, Tiemco hooks offer the best steel, the best heat treatment, the best chemically-sharpened points and the best designs, especially the SPBL series.  On the internet, Tiemco hooks are also discounted from time to time, but even at full price, they are worth every cent.  The hook quality is especially important in the smaller hook sizes.

Sisu:

Absolutely.  I am 100% sure I land more fish with the higher quality hooks.  Aaron and I did a comparison for a while between the TMC 2457 or 2488H with barb crushed versus the TMC 2499SPBL (they have closely similar but not identical profiles).  With identical rods and rigs, we found that more fish were landed with the SPBL hook.  This is especially true with smaller fish which are prone to nervous head-shaking.  I believe that Torrey (NymphMeister) will also concur.  My opinion applies only to barbless hooks.  Leaving the barb intact (which I never do) would greatly alter this comparison.

Please take a look at this thread:
http://troutpredator.info/fly-tying-discussion/czech-grub-hook-comparison-review/

As of now, the Knapek hooks have sort of fallen out of favor with me.  These hooks use a larger diameter wire in the construction, so the flies sometimes end up with a strange appearance.  We have also had a few problems with quality control of the Knapek hooks.

What is your experience?