I've been messing around with electronics for about 60 years. I built my first oscilloscope when I was around 12 using plans in the ARRL Handbook (I believe). It wasn't much of a scope but I learned a lot. Anyway, I've been doing this stuff for a while...
I had an old Dumont scope for a while but it was pretty useless. I move up to a 10 MHz dual channel Heathkit (which I built) and it was adequate for many years. When I retired, I treated myself to a Tektronix 485 which I still have. It is an analog 350 MHz dual channel scope that I picked up off eBay for $200. It's a great scope and I could get along with my projects using just this scope. Mostly I work on embedded stuff and, more often than not, FPGA projects. How do I get along? Well, I have the project generate very specific trigger signals so the scope is looking at exactly my point of interest. I don't need to store 2 days worth of samples and search through them, I know exactly what I am looking at. It's the user, not the tool!
But I never had a digital scope, didn't know if I needed one (and truly, I didn't) but I decided to see what they were all about. I liked the idea of 4 channels, that was a 'requirement'. In fact, it was the driving force. It's easier to work with SPI on a 4 channel scope. Easier, not compulsory. So, yes, I bought the DS1054Z KNOWING that it had warts at the margins. There's a lot to learn about using a digital scope. I didn't know anything about digital scopes, didn't know if I would even like one after about 60 years with analog scopes but there's no time like the present to learn.
Bottom line: I like the scope a lot. My grandson is just starting an EE program in college. He may get a lot of use out of the scope!
As to the Digilent Analog Discovery: I have the first version and I use it a lot - particularly on embedded kinds of things but also for messing around with analog circuits (including analog computing). There's nothing like a 27" scope screen! Given that the PC has two 27" screens, I have a lot of flexibility about what I display (including the IDE for code). There'a a lot of electronics that can be done with the AD as long as you can live with its limitations in terms of voltage input. Since I mostly work on 3.3V and 5V circuits, there is no problem. Of all the possible USB solutions, I like the AD the most. Two scope channels, two signal generators, dual power supplies, 16 digital IO (including logic analyzer functions), what's not to like? I can carry it in my laptop bag and I'm ready to work. Or play... I'm retired, I don't work!
I probably stand alone with the opinion that this device can put off the purchase of a scope for a very long time. Try doing network analysis with a scope! That is a very nice learning tool when it comes to filters.
I don't know what I can't do with a 1054Z so I'm no help. It does everything I could possibly imagine and a lot of things I will never use. Is it the end-all, be-all of scopes? Probably not. It has limited bandwidth so it doesn't properly display signals with high frequency content but neither does any other scope. Even my 350 MHz scope is bandwidth limited. The limitation just turns out to be a lot higher... That 100 MHz square wave is going to look a lot like a sine wave on a 100 MHz scope.
The measurement features are terrific! It's just a confidence booster when the scope gives a measurement that matches with what you already know about the signal. Being able to make detailed waveform analysis is terrific. Using the cursors to measure time between events is a lot easier than squinting to line the trace with the graticule. I actually used that feature yesterday to make sure I met the hold time on the chip select signal for SPI. Very easy to do! I was showing my grandson how RC servo signals worked - the scope displays the exact width of the servo pulse. No messing around, the number is right there on the screen!
I'm keeping my DS1054Z. I could have spent a lot more money but for my needs, this scope is perfect.