Re: Etihad Airways
I can't make general statements about Etihad, since I haven't seen all their aircrafts. My parents travelled from Lahore to London (via Abu Dhabi) on Etihaad in May en route to San Francisco (last segment travelled on Virgin). Their experience was outstanding. They were all rave for the airline in terms of timeliness, ground service, ticketing, food, comfort and baggage handling. Their experience may be a bit skewed since they travelled by Business class, and so they had access to business class lounges in both Abu Dhabi and Heathrow.
Re: luggage allowance, to my understanding, most airlines who travel over Atlantic have gotten to 23 kgs (50 lbs) allowance. Some airlines that fly over Pacific (Singapore) still allow 32 kgs (70 lbs). This change is in effect since summer last year. If this is important for you, do check from the airline. My suspicion is that it has something to do with how much weight should airport employees be required to lift, and this may be something coming out of Europe (so flights with stop-overs in Europe are impacted). Not sure, though.