Not all ICN-LAX flights are on A380. 744, 77W, 77E, and A332 are also used.

Since you already ruled out CAN (terrible idea anyway), I think you really need to decide if the long layover at ICN is worth the trouble to try flying on A380 (which you may not get).

I would stick with CI and transit via TPE because of the reasonable layover period - 7 hours on the ground via ICN is going to be a looooong wait.

Airport: ICN > TPE by a slim margin... ICN is big but new. TPE T1 is old but compact. But I don't know that I would make a decision on transit base on this.
Airport Lounge: Never been to KE lounge at ICN so can't say but I'm sure it is pretty nice
Equipment especially AVOD for children (movies): About the same. Both will have a good selection of English language programs
Seat comfort: In Y they are about the same. KE777 has slightly wider seats than CI747.
Layovers: TPE > ICN
Delays: Not much issue here with either. CI's LAX flights are usually protected from fleet disruption elsewhere due to aircraft allocation to China flights.