A friend recently bought the DS1202Z-E and it's very impressive for it's cost, though the price difference between the SDS1202X-E and the DS1202Z-E is pocket money, so the obvious choice is the SDS1202X-E imho if you only want 2 channels.
However I'm going for the SDS1104X-E, as it has 4 channels and dual ADC's (And has the option of adding a AWG and MSO later on)
IME these options are rarely taken later by customers due to their additional cost but initially like the idea but after time with a 4ch DSO prove to themselves the need for it is rare.
Those without a need for raw BW are quite well served by the good bit cheaper SDS1104X-U.
I was looking at the MSO option but I have also come to the conclusion that a 4ch DSO has some advantages over the MSO:
1. Checking signals on an i2c or spi bus "looks about right", then analog scope can confirm levels are OK;
2. Extra channels from the MSO make the display more than a bit crowded;
3. Looking at a serial bus vs a 16-bit bus is as well served by 4 channel as 16;
4. Highly integrated chips don't generally hook up with a parallel bus - 4 channel is more than adequate.
Rigol 4 channel 100MHz scope is slightly more expensive (£25) than the Siglent but the cost of adding the MSO is much cheaper (£180) and as well as the H/W there is no license required. The Rigol has 1 gs/s, 500 M/s and 250 M/s for 1, 2 or 4 channel so is closer to the -U version of Siglent. I'm not sure how they get to over 100Mhz with 4 channels running with only 2.5 or fewer samples - seems like guesswork. It has been commented before that sometimes paying a small premium for Siglent is justified.
Rigol vs Siglent also comes down to preference of the user interface. I do like the side buttons on the Rigol and the selection of measurements, but also the soft buttons underneath on the Siglent. Both scopes seem to have crowded the screen on the LHS and RHS so that the waveforms are smaller than they need to be and (as I read it) no option to hide the soft menus? The two-channel Rigol has combined the vertical V/div control with a 2 button selection whereas the Siglent stays with two separate controls. When you see the Rigol power-up, you immediately see green lights under the blanked-off areas suggesting it takes advantage of a common circuit board and an overlay that restricts the design.
There is a real danger that I may overthink the purchase and get more than what I need. That said I feel more comfortable with the Siglent 4 channel SDS1104X-E over the SDS1104X-U. In the US they aim for a $100 reduction but in the UK there is only a £50 premium. A scope is one of those things, where trying to economize now, can easily backfire later. When considering the price, where you buy it in the UK affects the total price (discount and delivery) so that has to be factored in too.
Simon