I have a Red Castle ShopnJog as my single pushchair. It has a lockable front swivel wheel, adjustable height handlebar, foot brake, hand brake, wrist strap and sizeable storage underneath the seat. The seat has 3 positions from slightly laid back to as flat as a bed. There is a good quality 5 point harness. Also it has suspension.
It is bulky if you have a small car -it won't fit in the Toyota Aygo without lying a seat down, but then again I can only just fit my umbrella fold in the boot of that car with little else! It fits fine in my estate! :)
It is a hybrid, as the name suggests, so is not as good as a pure out and out running pushchair with 20inch fixed wheels etc, but has been a great compromise for me and I have had it for 5 years now.
I borrowed a Phil n Teds for a while whilst I was waiting for a spare for my Red Castle. It was fine, it did the job and kept me running, but I was so happy to get back to my smooth Red Castle.
For running with a double, I use my chariot bike trailer! Absolutely love it but the 3 and 5 year old are fighting in it so double running days are pretty much over :(