for me its
A. I have a 2 channel scope and I’ve never had a need for 4 channels.
... if we talk about analog.
Of course I often need more channels, but then its digital. For this I can suggest a $389 Intronix Logicport logic analyzer with 34 channels. It can do whatever I want/need, with a trick it can also have a trigger out line to trigger the scope if you need a mixed signal view.
A benchtop logicanalyzer usually is a pain. With a PC based logic analyzer you can work with the signals 100x better, quicker and nicer than with a scope. However: beware of the cheap (<$150) logic analyzers, you will reach their limitations too quickly. The Logicport with its software is -in my opinion- still best of its class.
Yep, while it would be cool to have an Agilent MSOX3000 or maybe a Rigol MSO4000 they are kind of pricey. With either of those 2 extra channels is not a big extra cost overall and I'd for sure go with 4 channels.
Closer to entry level it would seem that a Rigol 2072 plus an Intronix LogicPort would be a relatively low cost and very high value way to go for users interested in reasonably high performance and digital signals.
The only question left in my mind (and the reason for the original post) is whether it might make sense to give up some waveforms per second, some memory, some screen space and maybe af few other features from the 2000 series and go with a DS1000Z to get the 4 analog channels, but either way one of these entry Rigols and an Intronix looks like a great combination.
It's hard to say who is happier - Rigol 2072 customers or Intronix LogicPort customers - kind of looks like a tie with many happy customers for each.