Really depends on the mood I'm in at any given time.
Hybrid:N. clipeata (clipeata x eymae) because it's very similar to N. clipeata, but takes a wider temperature range (oddly enough seems to prefer true LL conditions), and grows pretty fast compared to N. clipeata. Really shows nice exponential growth in both leaves and pitchers, much like N. truncata. It's also hairy and has peltate tendril insertions, which are two attributes I prize very highly. Did I mention it's also compact? I just love this plant. I do not know if it produces true uppers or what they look like if it does. The three largest I have ever seen are Michelle and Trent Meeks', EP's photos, and my own. That's not saying a lot, since there are not many pictures of this plant out there for some reason. My pitchers and leaves seem to be the same size as EP's photos, so hopefully it will start vining soon. All around favorite hybrid, ever.
Owned: N. campanulata, but N. clipeata is a very, very close second.
Pure: Toss up between N. campanulata, N. bokor, and N. peltata.
All time favorite: N. campanulata. I'm crazy about this plant. If N. pervillei wasn't so mysterious in regards to cultural requirements, it would be a two-way tie between the two. N. adnata is a close second. Very close. Hunted for this plant, as well as N. adnata and N. clipeata, domestically for about four years. The thrill of the hunt is what makes growing it all the more enjoyable. Plus, it's one of the few Nepenthes that I will have no problems with growing in college due to space. The fact that it never vines, but rather forms palm-tree like stalks, is a characteristic I prize it highly for. I don't like vines, but do like palm-tree looking growth, so it's really a win/win. The fact that the pitchers are so unique and it's a fast maturing plant is an even bigger plus!