I've flown EVA Elite alot, and SQ Economy, but not SQ A380 so can't comment on the particular SQ seat.

I'm 1.78m and SQ 32" (?) Economy was a bearable squeeze. By contrast, BR Elite is comfortable. 38" is quite a big difference plus the seat is wider too and with a generous recline. With Elite's 2-4-2 you have a greater chance of not getting an middle seat.

On the Combi flight you would have a good chance of getting a Deluxe (old version of Elite) seat because the cabin is quite large.. you could phone an EVA office if you can't get one online in advance.

Based on your 1.87m height, on seat considerations only I think it would have to be EVA.