There are other options. Last month, I was scheduled to go through ORD, leaving LAX around 9 am and arriving in DUB around 1 pm (don't remember the exact times). That non-stop flight from LAX looked nice, but I didn't want to arrive in DUB so late. As it turned out, there was bad weather in ORD backing everything up, so I hopped up to SFO and made the same LHR-DUB flight I was originally scheduled on. The SFO-LHR flight is a 777 (which I prefer over the 767). I had only a short layover in SFO. This is probably the best option for getting to DUB earlier in the day, but you do lose most of a whole day in LA at the start.

On the return, I took the 6:50 am DUB-LHR flight - and that was EARLY. I intended to sleep that night, but didn't end up getting any sleep at all. But it was really nice to be back in LA by 2:30 pm that same day.

In these decisions, I think the times are more important than the plane selections.