It sounds as though the OP only currently has stones up to 4k. While I own and love my Arkie finishers, I'm not sure he could reasonably bridge that gap with just a finisher Arkie. It would probably take a ridiculous amount of time. Possibly if it was a two sided stone and one side kept freshly lapped and the other kept prepped for finishing, but this may be beyond the purview of a beginner. I would recommend at least an 8k in between.
Of the remaining stones, I have only used the ILR, which I am currently testing. It is pretty decent, but the edges aren't quite as good as a properly prepped Ark or other superb finishers. Plenty keen, but not quite as comfortable for me. (Although I have pretty sensitive skin). Certainly shaveable though. As they are natural stones it's possible that others may be better or worse than the one I've got also.
I too have a Suehiro 20k, but have never used the 10k. I have heard good things about it from people whose judgment I trust though.