They grow out of their buggies after a while, so you need a pushchair when that happens.
We got a lightweight one for travel. Easier to get out the car but still use big buggy for day trips etc.
i had a Ocarro and it was just too small once my little got to 2, her head was literally in the hood. I got a silver cross pop stroller which isn't one of the mega lightweight ones but i found those ones were just too small so pointless. The pop is comfy for a large 2yr old.
we had no space to keep the big pram, so sold that and got a compact travel stroller that we use instead
Lighter and more compact. It really depends what you want from a buggy, I wanted a lay flat, big shopping basket, and full sun visor so went for the McClaren techno xt. It's not one of the smaller on the market but didn't want to compromise too much on comfort, still 5kg difference from my pram with an umbrella fold though.