Fist of all Interval trigger on Siglent supports two channels, it is equal to Rigol Delay trig.
Both have pulse trigger that is also same. Pulse trigger can be achieved with Interval (Delay), pulse is really simply a quick shortcut.
Second in DHO800 datasheet I count 15 triggers including serial ones. 12 analog triggers and 3 serial ones.
Siglent SDS1104X-E has 9 analog triggers and 5 serial ones (because it supports 3 more serial protocols). 14 total.
DHO800 has additional Setup and hold, N-th edge and Duration (which is variation of Pattern) trigger.
Siglent has more versatile Dropout trigger (Timeout in Rigol) that support state in addition to edges.
It also have time setting in Runt. In a same manner it has time setting in Pattern trigger, which covers many options of Duration trigger.
And 2more serial triggers and protocols(CAN, LIN).
Only 2 triggers that SDS1000X-E does not have are Setup and hold and N-th edge. It has 2 more serial triggers and protocols(CAN, LIN).
As I said before Rigol likes to play checkbox in a datasheet game. In reality it is not that simple. If you need CAN and LIN it is Siglent that has advantage..
I would say both have very good trigger set.