FlyerTalk Forums - Advice needed!

I have a trip coming up in November. IST - ORD. I need to use a voucher that I was given, so I can only book on britishairways.com. Looking at the possible itineraries for the outbound trip, I've narrowed it down to two possibilities:

Arriving on a BA connecting flight in LHR @ 19:00. Flying out of LHR the next morning, at 11:00, on BA. Business class on the a380 (the old configuration - 7 or 8 across). Arriving around 15:00 @ ORD
Arriving on the same BA connecting flight in LHR @ 19:00. Flying out of LHR the next morning, at 07:40, on AA. Business class on the 787-9 Dreamliner (the current cabin layout, 1-2-1). Arriving around noon @ ORD

My thoughts: I've yet to try either of these airlines (I've only flown Star Alliance in the past, and I recently switched to SkyTeam). This will probably be the only time I'll fly on a paid Oneworld trip - only to take advantage of the travel voucher.

The advantage of the BA option is that I'll actually have enough time to rest at an airport hotel, for a fresh start the next day. In addition, I've never flown on the a380. The advantage (or so it seems to me) with the AA option is that the cabin and hard product seems to be superior in every way.

Regardless of which itinerary I end up choosing, I plan to stay in Chicago in a luxury hotel overnight, to get some additional rest before preparing for a professional business event the following week. The ORD - LHR return will be on BA premium economy, on the a380.

Considering the circumstances I've outlined above, which option would you choose, and why? Thanks so much in advance.