Removable pedals are the go-to upgrade for Bromptons, either MKS EZY (more readily available) or Wellgo QRD (has a SPD clone that's compatible with Shimano cleats). Means you can take the left pedal off, so it doesn't stick out when folded, and swap between clipless and flats, which is occasionally handy. I don't think any of them are particularly cheap, though.
I got through several sets of cheapo folding pedals on my folding BSO before I discovered real bikes. The plastic ones were simply terrible, whereas the metal ones at least lasted long enough for the bearings to go. False economy.
I know some people are happy with a non-folding SPD or similar on the left, which doesn't stick out as much as a flat pedal. Depends on what you're doing with the folded bike, I suppose.