I've flown economy on A380s with Lufthansa and Air France to/from SFO. I'm 6 feet tall and found the seats comfortable, though no roomier than any other plane. But the cabin environment in the A380 is very good, lower cabin altitude (I think 5000 ft. versus 8000 ft) and the air didn't seem as dry as other aircraft. Also, the entertainment systems are pretty good for economy.
Malaysian seats ten across in economy, 3-4-3, over most of the lower deck (first class up front). And so your best bet is the aisle and adjacent seats in the center section. That way you have free movement without anyone else having to bother you to get in or out.