(I had promised myself that I wouldn't participate but... I'll repeat myself...)
The only difference is price! If you have $1500 buy the Siglent. If you only have $1000 buy the Rigol 5074.
I totally agree to this and I got them both, first the rigol for over a year.
Then sold for the siglent and until now never regret it.
Bigger, clearer screen, better touchscreen responsive, less lag between touching and acitvating an element than on rigol, looks "adulter" in general (no "mickey mouse" design).
Menu structure much more better, eres and 10 bit resolution, noiseless frontend, better than rigol (remind dave´s comment to this in his "review" of the mso 5000).
50 ohm inputs ( which is better than using a external termination), external trigger input...
But that´s what you expect, when you paying more.
The rigol could not get all it´s "horsepower" to the wheels, 8GSa/s are outstanding in it´s class( and not only there), also 200mpt Memory, 9" display, 2-ch inbuilt awg, lots of math functions including digital filters, 4 math channels (siglent got 2) simultaneously displaying, excellent waveform update rate and so on....excellent bang for bucks ratio.
I guess, rigol want to make it possible, to sell their own asic as cheap as possible and this is the result.
In pros but also in cons, which are :
-Display is somekind of dim( after modification it´s getting better, but in comparision to the siglent there´s still a difference), weak angle view, touchpanel is laggy and not so precise as on the siglent.
-Small fan, in the first edition inacceptable noisy, after the update less noise but scope is heating more up.
-Case look and feel cheaper, the design of the front are toy-style.
(BTW, it makes no difference to me, if a scope got separate or common vertical channel controls)
-No external trigger input, no autosense inputs ( I didn´t miss them).
-Math: You got more displaying channels, but all got the same trace colour...
-Weak support in case of firmware updates.
But...
For 1000 bucks it couldn´t get any better than buying this raw diamond, still I like it.
When spending appx 25...30% more, you get the siglent sds2k+.
If some things will be fixed/upgraded, this could be the scope for life for a hobbyist.
At least we´re talking about 1000...1400 bucks in both cases, which will be probaly the maximum range for most of the hobbyists.