long term, none of them are really worth a ****,,, we use 'CSS' which is great but most homeowner's are too cheap to make it worth elitecrete's efforts to market it to other than pro's.
They're all going to claim to be the best. Some are formulated so that they soak in a bit better, but are a bit more expensive.
The first thing you've got going for you is that it's a kitchen floor, which is not a high moisture area such as a shower. That alone means that sealing the grout is not the most important thing in the world.
Second, be sure to apply 2-3 coats of sealer. Not a huge deal, but every coat will help a little.