Interesting comparison of BR vs SQ vs QR in J. In my experience, all are usually excellent choices.

Hard product (seat): Q-Suite > BR 787 > BR 777 > SQ A350/777 long haul J
- Clearly QR wins on privacy, seat design, the works — provided that you are on a flight that has Q-Suite.
- BR, no surprises as to the seat, more consistent. The bed is more comfortable on BR than the others.
- SQ bulkhead seat avoids the foot cubby issue that the rest of their J seats have.

Service: BR / SQ > QR
- BR and SQ have remarkably consistent excellent service.
- QR service can be great too, but more inconsistent. Possibly the constant work of dine on demand keeps them too busy.

Amenities: BR / QR > SQ
- Very nice amenity kits on BR, QR; SQ just brought back kits but mainly on request.
- Very nice pajamas on BR, QR; none on SQ

Cuisine: QR / BR > SQ
- Yes, SQ has Book the Cook (so does BR; QR does not). But BR / QR have multi course meals from amuse bouche to soups and so on.
- QR has dine on demand and caviar on some routes

Lounges: QR > SQ >> BR
- QR’s Doha lounges are spectacular.
- SQ’s Changi lounge is lovely, luxurious.
- BR’s lounges at TPE, while serviceable, are not competitive.

Objectively I’d say QR and BR are better, but SQ has a consistency and route network that I like, so I fly them quite often. And they’re still quite excellent and reliable. But QR is clearly better on hard product, features, and so is BR. The key difference I think being that SQ has two higher levels of service: First and Suites whereas QR has only a rare F cabin on few aircraft.