I don't think USB logic analyzers suck. There are a couple of very nice ones around (e.g. Salae) and all you really want them to do beyond showing the signals, in my limited point of view, is to do protocol decode and that they do very well.
If you need to look at timing issues, like say you have a clock signal running through a couple of drivers or maybe want to create a differential signal using an EXOR and want to look at the skew between the two lines, you'll quickly find out that a 300 MHz scope has insufficient front end bandwidth/timebase resolution to measure the rise time accurately.
(interesting Keysight note)Anyway, I think you should not worry too much about this because a mixed signal scope like the Rigols you mention will do a fine job for most tasks.
Advantage being to show and trigger off either analog/digital channels and display on the same screen, disadvantage that the screen maybe is a bit crowded.
And since you say "digital stuff" I am going ahead and will assume you mean microcontroller/embedded systems - so look at busses, sensors etc. They'll do just fine.
It comes down to how many analog channels you need, and I would like to believe you can do more things with 4 channels most of the time (e.g. SPI) (and don't necessarily need the 16 digital ones). It is also quite a price addition compare to the models without the MSO option.
If I were to offer an opinion on this I would like to believe the DS1000Z-S Plus is better value, but the extra options (arb gen, mso) are going to cost a bit.
I think to recall that the built in generator ( 25 MHz, 14 bit, 16 kPts, 200 MSa/s) is a little less expensive than a comparable standalone Rigol arb gen.
It is very convenient to have those functions inside the scope though, to a point where when you need better functionality you will have to buy much more expensive generators anyway. Only thing I could think of is it a 2-Ch generator would probably be a more versatile choice in the long run.
EDIT, and the third thing you asked, yeah go have a look at what else is out there that could fit your price range from other Manufacturers and also look at the used market. Often older equipment one tier above can be very affordable still.