The 320 is the worst fleet to be. Lots of duty hours and little flying hours. You land in the morning and you are flying again in the night. But then again rosters in QR are a very...dynamic thing! You never know what tomorrow brings. For example the latest that the management came up with is the max 3 block days off per month. So even if you fly 777 you cannot get away from Doha more than 3 days a month. So you can enjoy lots of STBs and TBNs.
Good luck with any decision that you might take.