The Hyatt R Brisbane is unfortunate.
They took over an older somewhat trendy hotel and without proper re-investment pretty much left it as is.
I took one good look at the hotels sad looking photos after confirming a suite and canceled.The rooms look better!
Reviews were limited but I did hear complaints on other.
The Hilton is old and pricey for what it is but well kept with a solid small lounge (if open) and the GM is a good guy.
They have been Diamond friendly with upgrades.They never let me down

The Westin is the best looking up to date of them all hard product wise.
The service can be quite weak(hi staff turnover) and there are rarely managers on property
as they have more than one property to manage.Not a fan of absent management
Help the Flight attendant is flying the plane!
So if something needs to be escalated or requested you can wait 24 to 48 hours to hear back.

Hilton is better it has hands on management and they run a good show.
Hyatt's are much better in Sydney and especially Melbourne where I am always delighted to stay Hyatt.
One weird thing with the Westin is the in room safe.Its oddly under the built in luggage rack.
The dumbest thing ever.To access means removing your luggage each time.
The Hilton and Westin are a tie IMO both solid hotels in Brisbane and I'm not sure one can do much better
Find Brisbane pricing high.Sydney & Melbourne have much better value!Likely due to competition

The Hyatt has to be cheaper IMO as I perceive it to be a slightly lesser hotel and frequently its near the same in price.
I had an exceptional rate but still chose to cancel.In the end its where I will be the most comfortable
and have a good breakfast to look forward to each morning

Have a great stay whatever you choose.