What memory do you think is most reliable?

Have yet to have a problem with Sandisk. The only card that ever let me down is the Lexar. Kingston works fine as well, but my friend who is an engineer for Kingston says Sandisk makes a great product. Plus, the Sandisk is just plain faster than the Kingston.

When I got my first DSLR I bought two cheap Lexar CF cards and both of them failed within two years. Since then I have only used Sandisk Extreme and Ultra cards. I don't think that this necessarily means Lexar are no good, but I would stick with the higher quality line form any manufacturer and avoid the cheaper end of their lines.