I think Sidious loved Maul for the weapon he was, not as a person though. Sidious was only invested in Maul because he needed a weapon to help eradicate the Jedi, nothing more, he was not looking for emotional companionship. I am sure that Sidious felt a sense of loss when Maul died, but I am sure it was only because of the time invested in the training, and the disappointment of losing his apprentice in the first throws of the conflict. In essence Sidious loved Maul as much as a carpenter loves his favorite hammer, because Maul was not much more than that in the eyes of his Master. did he really intend Dooku to be his Varsity apprentice or just a place-holder until he could turn Anakin, whose power he sensed at the end of Episode I? I personally think that he intended Dooku to be his permanent replacement at the time he picked him, but Sith are opportunistic by nature. Once Sidious realized that the Jedi believed Anakin to be the choosen one, not to mention that Anakin was obviously powerful, Sidious then probably began to reconsider his choice of apprentices and plant the seeds for Anakins fall.