I know what you mean, but actually you can still record a part of handplayed music and put it in a loop on Seaboard, I'm sure. It's a basic feature which all modern synthesizers have. I do like the idea of Seaboard a lot as well, but honestly they all excited me to some degree, even the noisy jelly thing, because I do enjoy music making/playing process in general.
As for myself, though, I'd probably go with something classy like Fantom-G8. I don't know how many times I've expressed my love for this Roland model, even though it may be outdated today. I saw it in the news and I did like it from the first glance and then I had a chance to work with it for around a week and it proved to be amazing in every aspect.
Oh I also remembered about the HANG thing suddenly. It's a Swiss instrument handmade by a couple, who produce some small amount each year. I think it sounds good.