Well, that's not quite true - as a Diamond I can normally get 86A in advance (unless another Diamond has got it first), but they aren't normally generally available.

86H/K are the next best after 86A/C IMO, but not as good because they are slightly further forward which means that you have much less locker space beside you and fewer windows to look out of because yout legs will be beside the exit. (I am always surprised that this is allowed on safety grounds - when the seat is reclined it half blocks the exit, although I guess the thinking is that no survivable incident is likely to happen when the seat is allowed to be reclined; having said that, a power failure at altitude followed by an emergency landing and evacuation could leave it like that).

Others prefer the first row, but personally I don't like staring at a bulkhead and prefer to be able to see what's going on in the cabin. (For the same reason I tend to take 4A/K in F rather than many people's preference of 1A/K.)