Oscilloscopes - what specs to look for?

Noise and bandwidth are directly linked in most modern scopes. The higher bandwidth ADCs will also have more dynamic range when used at lower sample rates. This is probably the biggest price differentiator as well, as the cost of the ADC is usually the most significant parts cost of the scope. 

I was recently in the market for a scope to use for DIY audio purposes and decided to go for the Siglent SDS1204X-E. This is a 4-channel 200Mhz scope and cost about $750. This might be a little overkill, but offers a lot of nice features including FFT functions for distortion analysis. 

I started my career doing electronics design 40+ years ago, but it's been quite a while since I did any hands-on work, or bought a scope for that matter. The capability of the sub $1K scopes is mind-boggling compared to what I used to spend 10X+ that amount on a few decades ago. 

I didn't spend any time looking at the Uni-T, but did consider the Rigol and Siglent. Both are a great value. Keep in mind that with these lower priced scopes (including the SDS1204X-E that I bought), you can only use the full bandwidth if you are using half the channels.

So with the 2-channel, 200Mhz scopes, you're really getting a 1x200Mhz or 2x100Mhz scope. This is because they have a single ADC which is shared between the two channels (or used for a single channel if the second is disabled).

For most audio circuit use, this will probably be adequate, making these scopes quite a bargain.