Who said we are against them? Amano shrimp are larger and clearer, so they are less likely to be eaten. Depending on the betta, cherries may get on fine or be wiped out within a day. If the amanos work out (which they usually do), then cherries would be more likely to work out.Why is everyone against cherry shrimp? Cherry shrimp get a long with bettas very well. (Depending on the bettas temperament)
Personally, I feel that it's strange that people would put shrimp up to be sacrificed while at the same time claiming that it's cruel to keep bettas with fish. Both can be done, both can fail if you don't know what you are doing.
So I would do amanos first if you were to go for shrimp. Then cherries if you want more.