DuckDuckGo to the best of my recollection used to favour one of these options over the other however now it seems to support both syntaxes for bang redirection. It'd be really helpful if Interrobang could implement this too, firstly as it's easy to forget which way round it is, but also, putting the bang first is difficult on mobile keyboards when the autocorrect tends to try and associate the punctuation with the preceding word, and often there are no arrow keys to correct it.