Yes the Joie ones are good. Graco is the same parent company and a lot of their seats are similar. I'd go for Joie Stages, Joie Every Stage R129 or Graco Slimfit R129. Graco Extend is another option but it doesn't last as long as the others, as the headrest is quite short.
You could use the same seat in your partner's car, but if you're wanting an isofix seat, Graco Turn2Me i-Size is a good budget option or if you like the Cybex brand, Cybex Sirona Gi i-Size is a bit nicer than the Graco in terms of legroom for the child, fabrics, inserts and straps. Neither seat needs a base as the isofix is already attached.
Do you know how big LO is? You can probably keep using the Cloud for a while longer, since it's convenient. It has an 87cm height limit and the headrest space is generous. Although a lot of people do prefer to change seats at this age, it's perfectly safe to keep him in this seat until either he reaches 87cm, 13kg, or you've extended the headrest to the top position and his shoulders aren't fitting under it any more. If any one of those things happens then he has to move out but he can stay in the seat as long as he can fit in it safely. Some children can fit until they are about 2 years old.
The only thing to consider would be if your baby is bigger than average, you might want to consider a seat which would last him much longer; Tinyseats 2 might be worth a look - it's an isofix seat, so easy to fit in your partner's car, but it's also foldable and the vast majority of cars on the road (unless they are more than about 20 years old) have isofix these days so you could likely fit it into other peoples' cars too. This one lasts rear facing approximately twice as long as the other seats mentioned, and is a bit more expensive but the fact it does both jobs might make the extra cost worth it, especially if you are keen to stay rear facing as long as possible.