For the most part BLITZ BASIC and Dark BASIC Classic are very similar in terms of their variant of BASIC Syntax and Core Commands.
And I'd argue that these tend to be quite close to Quick/Microsoft BASIC (which was fairly standard for most 8bit Computers), unlike a lot of Modern BASIC.
Now, would I use Dark BASIC today?
Generally speaking, no.
Mainly because it's Compatibility (because it uses DirectX 8.1) is quite low... at least in terms of Windows Vista, 7 and 8., weirdly Windows 10 actually fully supports it provided you install the DirectX 8.1 Redistributable and package it with a key Runtime DLL (d3drm.dll, which I've attached to this post as it can be a bit tricky to find on "Trusted" Sources today). Still if you are only intending to release for Windows 10 (or Linux / Mac with Darwine) then it actually tends to work more issue free than Dark BASIC Professional.
While you likely wouldn't have heard this admitted on these forums back when they started (given the rivalry between Dark and Blitz BASIC) ... the reality is that Blitz typically was faster at Logic, 2D and 3D.
What Dark BASIC typically had going for it, was that you had a bit more Low-Level Access... which allowed you to do some "Cool" things (primarily with MemBlocks) that were much more difficult until BlitzMax., but at that point Dark BASIC Professional was released and it was frankly superior in Performance and Capabilities.
For better or worse... AppGameKit is actually the current iteration of Dark BASIC., albeit arguably stripped down in some respects and a bit to heavily geared towards Mobile Development.
Still it does retain a lot of the classic elements of Dark BASIC, and is running on a "Modern" (Portable) Graphics API.
There are plenty of Sample Code that's in the Code Snippets Area, provided you go back far enough (there is a search feature, and DBC Code is tagged as such typically) to see what people did with it and what's possible.