As you have a three door car, the original Joie 360 Spin and the Cybex Sirona will be no use to you for rear facing (which I'm glad to hear you already know about and want to do 🙂) because the button that you use to make them spin around is located on the seat piece itself near the child's feet. The spin seats that have the button located in a more accessible place for 3 door cars:
Joie i-Spin 360
Britax Dualfix
Besafe izi Turn/Twist
Recaro Salia
I'm not sure offhand about other brands, but these are the brands I would use anyway.
The other concern with 3 door cars and spin seats is that the back of the seat tends to stick out when you spin it, so you will want to do a check before buying to make sure that you can actually fit to spin it facing the inside of the car. They are generally designed to spin facing the door. You can spin it facing where the door would be in a 5 door car with the child in, but bear in mind that the child will need to not have their legs sticking out of the car seat or you'll have the same issue, their legs will be in the way. That's fine if they are old enough to understand being asked to hold up their legs, but a 1yo would not understand that. So you could tuck them in but if they kick them straight out again you will end up having to climb into the back to get them out.
It can work, I have heard of people using spin seats to enable easier rear facing in 3 door cars, I would just urge you to test it first as it doesn't work for everyone in every car.
As for alternatives, the Joie/Graco belt fitted seats are not bad options, budget friendly. Normally due to the belt path routing, this is in the way of getting the child in and out but in a 3 door car you would put the front seat down on the opposite side to the child seat and sit into the back holding the child on your lap, then lift them into the seat while sitting beside them. No belt in the way as this is going past where the "door" would be. I probably wouldn't bother with the ones that go all the way up to 12, as they tend to be a false economy as well as bigger and bulkier.
Or, as other people have mentioned, the Swedish style ERF seats are definitely worth a look. They fit compactly which is always a bonus and they are in the same region price-wise as the spin seats, depending on whether you look at more basic models or more fancy featured ones. For a 91st centile child, definitely worth it for peace of mind as you will definitely get to a safe age to move to booster without needing to buy another seat once the one you buy now is outgrown. They can be a bit of a pain to move from car to car, but honestly any toddler seat is. If you will be moving it to one specific car infrequently, then you can just get a second set of tether straps and install them in the other car (they don't get in the way) and then it's no more difficult to move than any other kind of car seat.
On to some questions...
Will she have to be forward facing sooner in the Joie seat?
With the spin seats, they have the same weight and height limit for forward facing and rear facing, this is around 18kg or 105cm depending on the exact seat model the kg vary a little, but not much. For a 91st centile child this is roughly 3 and a half years, so if she continued on her current line then you'd be looking at the seat being totally outgrown potentially at about three and a half which is a bit too young to move to a booster seat for most children. You might get lucky and she will wait and have her growth spurt after her fourth birthday or she might be really sensible at 3.5 or she might just slow down, but on the other hand she might get even taller or have her growth spurt earlier or she might be just four but you still feel anxious about moving to a belt.
But in these seats, unless they do up to 12 years (which I don't recommend in general, these all-stages seats are almost always a false economy and make too many compromises) when she hits that 18kg or 105cm, you don't turn the seat forward facing and keep using it, you have to buy a new seat entirely. And for the ones that go up to age 12, when you reach the rear facing limit, you have to use it as a booster seat when you turn it around, you can't normally keep using the harness to any higher limit forward facing.
The age 3.5 thing is the main reason it's a good idea to consider a seat up to 25kg/125cm as it just eliminates the whole - is she about to outgrow the seat, is she sensible enough/old enough for a booster, what should we do which occupies the whole of that fourth year. They will fit her until approx 6-6.5 so even if she had a mega growth spurt and outgrew it 6-12 months earlier than that (unlikely) she'll definitely be ready for a booster and you could even just use it until you want to switch to a booster (perhaps around 4-5 ish) and not max it out if you don't want to. It just gives you the freedom of choice.
Difference between Joie 360 and Joie i-Spin
As mentioned, the button to spin is in a different place. The inserts are slightly thinner and less tricky in the i-Spin, they can be a bit awkward in the 360 spin. The i-Spin has an extra recline setting to account for the thinner wedge insert. It has a memory foam headrest for extra comfort and side impact protection. It is approved under the newer R129 legislation and i-size compatible. It has much better side impact protection. It has a height limit of 105cm whereas the spin 360 has no stated height limit, just when head is over the top of the shell (often fits to approx 110cm) and goes up to 19kg on the weight limit whereas the 360 spin is 18kg.
Cozy n Safe BTW are a British company but I believe they don't manufacture their seats, they just import them and distribute them with their own covers on. (I might be wrong - they might be the base maker for the seats I've seen with the same shell under different brand names in Europe). Either way, that isn't a reason not to use them, but just to clarify. They can also be good for budget options (especially harness to 25kg which is rare) and they have a few belt fitted options however beware as some of their seats have lower rear facing limits than the Joie ones. Same issue with BabyAuto who are Spanish.