One of the things I've always admired about Kate Mulgrew as an actress is that she's been able to achieve a reasonable level of success without being a great beauty, incredibly sexy or having a great body shape. I once heard an interview with Kate on this very subject where she acknowledged that she lacked the overt sexiness and beauty of many in Hollywood. In some ways, I guess that's why she hasn't landed a lot of highly commercial (but shallow) roles. This is true of many of the actor I enjoy watching eg Eric Stolz, Christopher Walken, Glen Close, Dianne Wiest.
Having said that - beauty/sexiness etc is a very personal choice.