Good question. Up to now I just thought FT over DS is more secure, but that does not seem to be the point.
I found this, also discussing advantages/disadvantages of the 2 approaches:
In short if I understood that paper correctly it looks like ft over ds is the better approach if the network between the APs is not too crowded, because the client only switches channels in case it definitely roams, whereas with ft over the air it has to pause the current ap to contact the new one.
And basically with your nickname "wired" you definitely should choose ft over ds 