Assuming you live in a place you can get Apistos in an Lfs I would say see what your lfs has or can order. Cacatuoides is a possibility, personally I have eunotus which do well in neutral water and would recommend trifasciata. You may want to mail these - you see some nice fish on aquabid. A lot of the apistos I have seen in shops in visits to the US have been so poor I would be loathe to buy them. The cacatuoides I have seen have had distinct signs of inbreeding , and over production.
I would still say get a pair - a single is not likely to be the most amazing fish in the world - a pair is better. In a 10 you put in a ton of small 84 to 5 inches) pieces of wood for caves, a pair of trifasciata, a very small fancy plec like a clown (? vittatta), and 6 cardinal or dwarf pencifish, a little bit java fern and have an awesome mini biotope