Prefer no rights with flexbility to work when and where you want.
With rights, you're probably expected to work fixed, set shifts, and accept every job, including pool otherwise you'll be in breach of contract/agreement. You'll also be expected to wait in certain areas and you may not be paid to drive to the first pick up of your shift, and going home after last drop off (similar to working in any other job, i.e. office, Tesco, etc., they don't usually pay your commuting time).