I guess I've got to take up the cudgels for the DP800 once again...
Besides the presence of the decimal keypad, there are two more things that I really like a lot about these PSUs: The rubber bumpers, especially those at the back, make it possible to operate the PSU resting on its rear face and to place it next to you on the floor. I found that VERY useful in several situations already. They also permit to set down the instrument on any face except the front (the terminals project).
My second "thumbs up" is the general build quality -- it's literally made like a tank. Siglent also appears to be decent qualiy but definitely not as rigid as the DP800. Korad or Owon and the likes with these flimsy reinforcement straps screwed directly to a tiny tab of the plastic front panel, making the latter a structural component of the (quite heavy) PSU, is something that I wouldn't consider adequate. But of course, electrically these power supplies may also do a good job.
Regarding the Rigol DP800 family, nowadays the issues of the early revisions that Dave highlighted, have been completely solved.
Price-wise, if you're prepared to spend 400 euros, I think some 70 or 80 more to get a more decent unit, shouldn't make much difference. If, on the other hand, your "comfort zone" stretches up to 250 euros, the only options will be the "cheapos". Depending on your application(s), you may even get along fine with a switcher, but if you only once need to check some really sensitive circuitry, you will be at a loss.
In the end, it's your decision -- we can only help with thoughts and information to find the best solution for yourself.
Cheers,
Thomas