Other DSOs to stay away from are Uni-T.
Hanteks are a mixed bag. The 5000D series is hackable and the hardware and software have been extensively reverse engineered. Related series like 5000BM are similar. And occasionally Hantek publishes new firmware. But Hantek is slow to fix bugs. Still better than others, like Uni-T, who don't fix anything.
Owon initially needed a little bit of convincing that their stuff wasn't fault free. Then they did work on the firmware and even did some hardware changes. But it seems there are strange and difficult ways to get a firmware update. They haven't been hacked. People have reported surprising good communication with Owon service for a Chinese manufacturer.
The Rigol DS1052E has been hacked and the hack became so popular that there have been vendors selling the DS1102E for the same price as the DS1052E, otherwise people wouldn't buy the DS1102E at all. Rigol support is strange. My experience with them is very bad, i.e. no support, rarely any response, and if a response it was nothing but lies. Others claim they occasionally had Rigol people really talking to them.
Atten is mostly junk. Same with Siglent, which is just another brand / undercover operation of Atten.
Little is known about other brands like, for example, Ypioneer, Tonghui, or Lvyang. They occasionally find their way on the western market.
Instek and Hameg are a level above the DSOs mentioned when it comes to quality. Although we had big trouble with getting an Instek DSO serviced by Instek. We finally had to throw it away.
Another level above are the Agilent InfiniiVision 2000X and 3000X series.
A strange beast are Wittig/Weltec DSOs. They were a German company that went bankrupt, not the least because their DSOs had horrible firmware. Batches of NOS of theri DSOs occasionally show up on eBay, sometimes as no-name DSOs. There is a group who has written a replacement firmware as open source for them. If you are interested in hacking a DSO, as opposite to using it for measurement, this might be an interesting choice. Another one would be the Hantek for this purpose.