I have been to Queens several times and never to Halle but it's clear watching Halle that its centre court is streets ahead of Queens and is already Masters 1000 quality. Queens can retain its 500 but earlier maybeAnd also, Halle has already the centre court ready for a masters. They have lots of surroundings space to expand with a few more courts. As other people have mentioned the catering, hotel, general facilities is top nutch ordnung muss sein.
All they would need is a bigger Court 1.
I have never been there but it is my impression that Queens need a bit more of work.
Whereas Queens doesn't have parking it's slap bang in the middle of a residential area and there's no way they could ever play under lightsBeen there twice, 2018 was nice Federer saving match points vs Paire and Coric playing out of his skin in the final to beat him.
Very nice facilities, the parking was a nightmare tho, you have to park like 3km away!