A T-Rex, as a pet, it would keep my ex, bullies, police, lawyers, neighbors, Jehovah Witnesses , Xtians, bill collectors , solicitors and others that I can't think of right now, away from me. Also my dog Leo wants a playmate, (T-Rexes are trainable no matter the lies said about them).
I wouldn't clone a person. What we love about a person is their mind and in order to reproduce that, we'd either have to have mind-uploading technology, which we haven't achieved yet, or we'd have to re-create every event of their lives down to the smallest detail, which is unfeasible.
An animal would be much easier and simpler, and there'd be more chance of the same personality reoccurring. In which case I'd clone my best friend's cat, Kiki, a sweet little black kitty who was full of love. I was cat-sitting for him and his family while they were out of the country when she got sick and I couldn't read the signs (I thought she was just getting clingy because she missed her regular humans) and had no transportation to take her to the vet anyway. By the time they got back to take her to the vet her hyperthyroidism had done too much damage. She got terribly such and we had to put her down. I still kind of blame myself, a bit.
My good friend, Laura (not her real name, she likes her privacy so I'll respect that). She always thinks of others before herself. A while back she nearly died on the way to hospital in an ambulance and when I saw her all she could talk about was how am I getting on? This didn't really surprise me because I know what she's like but the one time she should have been putting herself first she didn't even do that then! What a star and a totally wonderful human being - an example to us all! I would clone as many of her as possible - it really would make the world a much better place!