also there is something to be said about the playfulness of the almighty Tiger Barb. also go to your local fish store and check their stock this can also affect personal choice ,budget, sometimes you can only work with what you have got
good luck with your choices. they are all good choices!
TIGER BARBS!!! For real though there are a ton of easy to keep good looking fish. I think the Easiest to keep are ones that match your water conditions and don't require any (or very little) adjustments to the water.
Plastic fish are easy to keep also........just playing.
Tiger Barbs are harder to choose tank mates for since their such nipping fish.