Think about a normal outing: the surface you walk on, stairs you need to manage and space in your car. A stroller that suits that routine will be easier to use.
Britton Helix
Britton Helix stroller has front and rear suspension, 18 cm front wheels and 25 cm rear wheels. It folds with one hand and includes a rain cover, foot cover and Maxi-Cosi Cabriofix adapters. The listed child weight limit is 15 kg. Confirm the exact car seat and adapter combination; adapters are not a car seat.
Britton Allroad
Britton Allroad stroller weighs 9.7 kg and has 22 cm front wheels and 24 cm rear wheels. It includes a rain cover and foot cover. Its manual lists a 23 kg child weight limit. Compare that with your needs rather than assuming all Britton strollers have the same limits.
CBX Leotie Pure
CBX Leotie Pure stroller set includes a reversible seat and a separate carrycot. The carrycot is listed from birth to 9 kg; the seat from approximately six months to 15 kg. This may suit you if you want separate configurations for the early months and later sitting.
Try the everyday tasks
Check folded dimensions against your car, and consider lifting the stroller as well as pushing it. Confirm the complete set and read the instructions for the configuration you will use.
Use each model as intended
Follow its age and position limits, adjust the harness and check brakes and frame locks. These strollers are not jogging strollers. Keep your child away while folding.