The share class offered to investors on Crowdcube should be Ordinary Shares with pre-emption and voting rights. The shares will be issued to Crowdcube Nominees Limited to hold the shares on behalf of investors. You can elect to set a threshold above which shares are issued to investors Directly and not via Crowdcube Nominees. This threshold should be at least £20,000.
You should consider how investors are likely to view the rights you are offering - severely restricting the rights and protections available to investors may reduce your chances of a successful round.