I hear the Churchill III's a rather good Tier V premium, though like any other Churchill its playstyle gets some time to get used to.
Speaking of premiums though, I love my Super Pershing, aka T26E4. Its mediocre gun isn't much of a problem if you aim right, and you have all the time to aim due to its miraculous spaced armor that completely negates high-damage shots like a sponge (I call it "Black Hole Armor"
). It actually plays rather similarly to the Churchills, except that your armor scheme is superior due to the sloped spaced armor covering most of its front, and you can peek around corners better. A good game with it nets me about 30-40k in profit, more if I do extremely well.