Reflectors, optics and lenses have a big part to play in how we percieve the light being emitted from our leds. Then the leds themselves have varying properties within the same make as the 'tint lottery' guarantees that one led will have you singing praises and the next will have you going for the bin (trash can).
XR-E's have been my least favourite. It's a mix of XP-E's, XP-G's, MC-E's and an SST-50. I like them all for different reasons and it's more a combination of reflector design and tint that makes me like or not like an led.
Can't really say I have a favourite, they all do different things and that's why I chose them. It's like saying which of your children do you love the most, as anyone knows, that is not a question you can answer.