Things I wish it would have:
1. ge and gE
2. Marks like ``
3. Changelists so I can g; and g,
4. Visual block replace.
5. Something like the surround.vim plugin to surround blocks of text.
The one thing I absolutely love is the keybindings support so I can map something like <leader>f to Open Files (a fuzzy finding tool that comes with Xcode).
Or my favorite, <leader>d to Look up documentation under the cursor. No more option+clicking with your mouse! (Useful for Swift to check what type the compiler has inferred)
Here's a link to my ~/.xvimrc if anyone wants more:
s StepInto <Space> StepOver f StepOut b ToggleBreakpoint c Start K StopDebugging u (Move up the stack) d (Move down the stack) B BuildSolution C Compile <M-'> GoToNextLocation
I also remapped C-d/C-u to enter/exit this debugging mode, but since I never use VS for editing I mostly just keep the keys remapped to debugging keys.