I went with 55/100 watt H4 bulbs (in Autopal housings). That works great, has "normal" low beams that don't annoy anyone, and maximum high-beam power. The difference in my lights (half harness, half new lights) was amazing.
griff95zj, what projector housings are you using? I've never seen any real projector housings that would fit in an XJ. What kind of pattern do they produce? I'm a big fan of a legit projector HID set-up (they put an unbelievable amount of light down the road where you need it, and less into the eyes of oncoming traffic than a regular halogen headlight), but am a huge opponent of "HID conversions" (stick a pair of HID bulbs in a halogen housing, and you put LESS light down the road than the halogens, and spray a huge amount of light around in useless, annoying directions - it's a worse "upgrade" than tinted headlights, IMHO).