A step up from ed but a step below vim is nvi.

I've always preferred nvi over vim because:

1) there's no lag when I scroll up or down through a file line-by-line,

2) it shows a list of matching files by default when using tab completion in command mode (same as bash), vs picking the first matching filename, and

3) it uses fewer resources when you screw up (http://galexander.org/vim_sucks.html)

I used to think that the lack of syntax highlighting was its biggest weakness, but now that's apparently a virtue :-) .