It really is hard to generalise with all anemones. BTAs are probably the most likely to be eaten- peppermint shrimp are one of the most likely eaters as well as angels, butterflies and even some other fish like tangs and rabbits. Being eaten by a fish is one of the less likely causes of death for an anemone though and a host clown will likely do a fine job at protecting it. Having food always stolen is another problem which shrimp, fish and just about everything else in the tank can cause.
I have regal angels, rabbitfish and a copperband butterfly with my magnificas and none of them eat or are eaten by the anemones.
Almost all fish are going to be safe with a BTA as far as themselves getting eaten.
On the other end of the spectrum you would have something like a haddoni carpet which is likely to eat just about any non clownfish in the tank.
Most other anemones are somewhere in between for both problems, but the big issues with anemone death continue to be powerheads/overflows, insuficient lighting, and buying unhealthy specamins.
