You mentioned wanting to improve your defense and I think LB khufu might marginally be better than LB Hypnos for that. So if defense really was the only thing you cared about…then maybe khufu. But if attacking mattered at all, I’d choose Hypnos.
I have both, I can say without a doubt Hypnos is better. Someone mentioned panther, listen, that 7th tile panther needs to fire is hard to find at times. The 6 tile buff block is insanely strong. At 9 tiles he debuffs before the hit and blocks as well. His skills are absolutely ridiculous. Not as good on defense but still pretty darn good. The negative mana generation is awesome. So in my opinion, the speed and skill of Hypnos outclasses khufu.
I’ve used khufu on defense in a lot of configurations, he’s not great. Im not sure what your defense is now, he may be a huge upgrade. Regardless, on offense he can be difficult to use without a mana booster, teteshiri, Brontes, c sif etc. he’s just more limited in comparison to Hypnos.