[mo_42]

In These cases I'd recommend text objects. For example,

  ci)

Will delete everything inside parentheses and put you in insert mode.

Even works for HTML tags with t I think.

Edit: should be ci) to preserve the parentheses.

[ackyshake]

Text objects are cool, but `ca)` would remove the parenthesis too. There's no shorter way to get to `my_func(foo);` when your cursor is at the comma, than using the motion OP indicated.