So quick question. Is there an acceptable emulator for speedrunning Suikoden?

So far as I know no one's really tested differences for emulators. IMO any should be fine. I think RNG mechanics might differ between emulators though. Supposedly, bizhawk is the most accurate but I get a lot of lag using it so maybe it's not the best option for you. If I had to recommend one I'd recommend pSX since it seemed to have no graphical glitches unlike ePSXe. But any emulator should be fine :)