I second the ID11 as you can't go wrong. HP5 isn't under normal conditions a high contrast film, you have to push it; but normal exposure & developer times with HP5 should show the films long shoulder.
In other words as long as you didn't under-expose you'll be fine, to be on the safer side higher dilution will give less contrast.
Rodinal is interesting, as you can get some great results with surprisingly fine grain even when pushing....
Acros at 12,800 in low contrast lighting Rodinal for 45mins 1:100
A slightly thin neg, with no tones but I am a believer in the church of the holy Rodinal