the 0x token sale was the best I have ever seen. a registration period where everyone who wants to participate in the sale has to register and the total amount of tokens to be sold is just divided by all people who registered. In the first 24 hours everyone who registered can use his cap and the remaining tokens are sold after 24 hours in a second sales round with an increased cap per person. this model is fair for everyone and guarantees a good spread which is really important. I wish there were more ICOs like this.

The worst model is the ignis token sale where 1-10 accounts were able to buy the whole supply in a few seconds and everyone else left empty-handed. many people including me bought nxt just for this ico and after an unsuccessful try buy ignis nxt got dumped, resulting in 50% loss of value for nxt.