What is the most effective preparation of oestrogen?

There isn't really one form of oestrogen that is more effective than another. The method which you take your hormones largely comes down to personal preference. Generally speaking gel and patches are the safest, easiest and preferred methods among patients, as they avoid the need for liver absorption as with tablets. Gel is the easiest to adjust in terms of the dosage (increasing/ decreasing the amount of pumps) but the potential down side is it needs applying daily which can be inconvenient. Patches are only applied twice per week which many find more convenient, but supply of these from some pharmacies can often be an issue. It is worth considering the costs of these items as well, as gel and patches vary in costs dependent on pharmacies (gel is usually cheaper).