Risers on most of mine, Nukeproof low rise on 2 (cut to 740mm), Sunline V1 745mm on another and my very little used Inbred SS has Nukeproof flat bars (but a fair few spacers under the stem).
My saddle if almost certainly higher than most riders though so risers are a good option for me as the bars are still always lower than the seat. Shorter riders may prefer flat bars to keep the front end lower (Clubber excepted) but as with anything like this, there’s no accounting for personal choice.
One thing i do hate about flat bars is the pain of turning them upside down for trailside maintenance etc, risers provide a nice stable platform and you don’t scuff your stem or brake/shift levers.