Hmm. It depends. The centerpiece of your tank can be different depending on who is viewing it. If someone not familiar with fishkeeping is viewing, then usually the largest/most active/most colorful fish. If a fellow aquarist is viewing then it may be whatever fish is hardest to keep or rarest, which may be different than what a non-keeper would think. For example, someone with a South American tank may have rummynose tetras and some small angels. A non-aquarist may see the angels as the centerpiece becuase they're well known, easy to ID, and often flashy looking. However to me, the centerpiece would be the rummynoses becuase as an aquarist I know they can be moderately difficult to keep, and often a bit more rare. I'd be drawn to the rummynoses more than the angels.