As for the buckle type.. its all about personal preference.. if you prefer a lower profile look, the Thumbnail buckle is your friend. I personally prefer sewn-in look, but sometimes like to be able to switch the buckles depending on the watch, so it is less flexible that way. Your 88 is not a historical model so you could pretty much put whatever you like on it and you wouldn't be breakin' any rules
Toshi straps are not softer than OEM straps, just so you know. The softest straps I've experienced I think would be the Wotancraft XX Vintage straps.