Learning in the editor
I do think Playground is an important part for people to get familiar with VS Code's editing features and should be a part of the welcome experience.
Being able to try the features right in editor is much better than reading docs in a browser and come back to editor.
The page as a dashboard
Another vote for B here, perhaps with a button to expand (& pin) recents to fill the page...for those who want recents as the primary function of their welcome page, after using the application for some time.
Also agree that playgrounds need to feature here somewhere, but I guess that would be under the learn tab.
What do you think of moving the "New File", "Open Folder...", and "Add workspace folder..." buttons above the recent files/folders list? They could be represented as horizontally stacked icons, possibly with titles underneath. That way, the "Start" section could be removed, which should provide enough space for the "Customize", "Learn", and "Help" tabs to be broken out into vertically stacked sections.
The page as a dashboard
I prefer D the most and here are my 2 cents. Before I'm super familiar with shortcuts of Open Recent and Open Folder, I used Welcome Page as my dashboard. I bind F2 to command Open Welcome Page and then everytime I just press F2 and then
Room to scan
I prefer B... I think giving regions of space to each set of features could help users process them more quickly/easily at a glance. The background on the right side creates a nice separation. The tabs in the main content area allow a few items to be tucked away a bit, reducing clutter. It'd be a nice bonus if it retained the state of your selected tab.
When the layout shifts
Just a quick proposition, some user might not understand why their view is changing (or even when it's changing). So perhaps adding a dropdown to choose the view that the user would want might help!? I basically think of exactly how that can be customized in Outlook with Pane View customization.
I like C and D, perhaps sort the buttons on D by category like C, lower that container down so it's centre with everything else, and center the Show welcome page on startup checkbox
The empty first run
the folders list looks really empty. can icons be added next to them? if a folder is mainly javascript maybe display javascript icon?
The empty first run
I like the focus of C on 'Recent' folders. Is there a good way to use that space when there are no recent folders yet, like on first startup? E.g., by using a subpage switcher like in B.
Let extensions in
I really liked the new mockups, specially the exploration C, but I would like to comment a different area.
Is there any chance (or had any conversation about) allow extensions to contribute to certain sections of the Welcome Page?
Let extensions in
Really loving exploration C (maybe logo could be a little bigger) and would be wonderful if extensions could contribute to the page. An example could be a GitHub extension to provide open issues or remote repositories.