Unfortunately that one linked doesn't do very well in safety testing.
What's your budget?
I really like the Britax Advansafix one as when it converts to a booster seat you get a really nice quality booster seat which is rare. However what I'd like to do before I bought it would be borrow a 9 year old and see how comfortable it is for the later stages, because I'm not sure about that given that it's on a base.
For a budget seat look at Joie Elevate. Not much more than the previously linked one but does better in safety testing. It's still not great though, but would be better than a booster seat on its own.
If you'd like to keep your child in a 5-point harness for a bit longer (25kg/up to about 125cm height, rather than 18kg/about 105cm height) and you've got a top tether point in your car look at the Joie Bold or Cosy n Safe Excalibur. That is an extra step for moving between cars though, but may be worth it if you don't want him in the adult belt too soon.
You could if you want to go for something like the Joie Every Stage/Verso which will have him sitting rear facing (children often find this fun) until he's 18kg at which point he can use the seat as a booster seat forward facing. Worth noting though that this seat is not recommended to be used forward facing with the harness, as the crash results for it aren't very good.
Otherwise for a bog-standard 123 seat, Britax Evolva is supposed to be pretty good.
I wouldn't currently recommend another impact shield seat. I had one for my DS1 but I think their day has passed and I'm not sure they're very highly regarded any more. I think they are OK for children on the smaller side (but rear facing is even safer for those children, and much easier to achieve now) but once they're close to the weight limit of it they actually seem to perform worse than a booster seat, so not a very good idea.