One episode I've always taken to but rarely hear much about is "The Seventh". It's not the most ambitious or complicated episode ever, but it's a nice, pleasant and mostly character focused episode that did more to sell me on T'Pol than all of season 1 combined. Plus the Archer/T'Pol interactions were nice and desperately needed to distract from the awfulness of "A Night in Sickbay", just two episodes prior. I'd say it's probably my favorite of season 2. I thought so at the time and after having recently gone through the whole series on DVD, for the first time since the series originally aired, I hold to that opinion.
Outside of A Night in Sickbay and Precious Cargo, the season on the whole is better than I remembered.