It will depend on the use you are putting it to. Will it be used for a lot of walking (cross-country, parks etc), or urban use? Will it be in and out of the car a lot? Will the trips be long distance or short hops? What kind of boot space do you have? Do you want Isofix for placing it in the car? And very importantly, what is your budget?
We used a Jane Carrera C with a Matrix seat for our first - it was ideal for long journeys as the seat folds flat, but the seat was heavy for carrying around. That pram lasted a lot of walking, and several flights, and is one of the easiest prams to push about. For the twins we got a Baby Jogger City Mini as it folds very, very, very quickly, and time getting in and out of the car is important this time round. It's not a travel system, but an attachment can be obtained to turn the single seater version into a system. I'd readily recommend either.
Your needs will determine the best for you. Have a think, and then look about for something suitable.