If you like the completion dropdown, and use Emacs, you may like term-mode extended with my readline-complete.el [0] and auto-complete-mode. Screenshots on the page.
As an aside, you would not believe how difficult it is to read completion data from readline. There is virtually no useful documentation on this matter; many readline settings make the task impossible; the --More-- menu requires your scraper to be interactive... you'd think there would be an escape to return the necessary data in a computer readable format, but you'd be wrong.
On top of that, some programs use mechanisms similar to but incompatible with readline, see Haskell's GHCi and haskeline.