The vast majority of the STOs we have worked on relate to the sale of ERC20-standard tokens on the Ethereum blockchain.
Ethereum is perhaps the most well-known and established blockchain platform available and, with its scripting and smart contracting ability, is comfortably the most commonly used blockchain in the STOs we have seen.
However, we have recently noticed what could be the beginnings of a trend towards the use of other blockchain platforms for STOs. We have seen Stellar emerge as a blockchain platform of choice for tokens linked to payments and also seen entirely new blockchains being developed for specific projects. Time will tell if this is the start of a new trend away from Ethereum or if it is just an anomaly.