I have both. I first got the DS2072, then the DS1054Z came along and for $400 AUS, I thought it's time to just buy it and see what it's like and stop wondering if...
And after a few upgrade codes applied I have two excellent DSOs.
I like:
DS2072 - screen size (good for older eyes), big-ass mem depth, bigger control size for big hands, the memory playback control! (worth $200 or more alone..), bus decode from memory (i.e. SPI decoding of sample frames of data captured in mem)
DS1054Z - serial decode seems more robust, in particular SPI when using CS instead of time-out to define data words. 4 channels. 4 probes. 4 good colours for each channel.
the display is brighter and I do not miss the lesser number of different colours of the traces. You still get a very good CRT like persistence effect.
I do NOT like:
DS2072 - SPI decode which mandates using time-out as the only data word limit. I would love CS as an option.
the LCD is a little less bright than I would like but you can see it fine in most indoor lighting situations.
DS1054Z - down to 250M sample/s if using more than 2 channels. Navigating the deep sample memory is crap, really, compared with the lovely big knob devoted for this purpose on the DS2072. Seems to respond a little slower to user input (try vertical position changes to one channel when 3 or 4 are enabled...). It does NOT decode bus data from memory. This is nearly a showstopper to me. There is not enough spare room in the PLA's to permit adding this feature, according to Rigol so it's not going to happen. And so you are forced to capture a huge string of sample data in single shot, and pan through time to find region of interest which will decode properly.
DS2072 $900 v DS1054Z $400
I still find it hard to choose one, and sell the other. Right now I'm playing with microcontroller driven boost dc-dc converter experiments and 3 channels is very handy indeed.
It depends what you are going to use them for.
In a perfect world we all would have $15K+ Tek/Agilents/LeCroy loaded up with everything.
But in the real world what to choose...