All of these drugs are capable of preventing estrogenic effects. If you are worried about the side effects on your cholesterol levels as a result of driving your estrogen levels too low, I would strongly suggest that you
A) stick to nolvadex and clomid (which may be slightly beneficial in this regard)
or
B) get blood tests done if you decide to use aromasin, arimidex, or letrozole (these compounds are easily capable of driving estrogen levels too low, which can wreak havoc on your lipid profile and triglycerides)
These methods will ensure that you do not get gyno and keep your estrogen levels just in the comfortable, healthy range.