I can only comment on two travel systems as that is the two we have had. We bought the Silver Cross 3d travel system for when our nipper was first born with the ventura plus infant seat. It was ok but after a while some things about it started to grate, it wasn't light and lifting it in and out of the car was a pain and it took up a lot of boot space due to the shape it folded down to. The other thing which was more of a pain was that due to it having double wheels in each corner, the front wheels each side aren't in the center of the pivot point so when you went to turn it there was a lot of resistance as the four front wheels lined up to where you wanted, that made pushing it with one hand hard work. Also the wheels are too small so on uneven paths the wheels wouldn't just roll over uneven paving slabs etc were bigger wheels don't have any trouble.
Anyway we were due to fly to the states in April and wanted a stroller to take with us and into the plane. The silver Cross was to cumbersome for this so we went looking in mothercare. When we started looking at the McLarens and other buggies the Britax B-Mobile 4 Stroller caught our eye it was the same weight as the tube construction strollers but with a much better frame, it folded in two in a really simple way which ment putting it up and down was easy and the wheels just glided along really well even one handed was a breeze. It also took the Britax infant seat which ment we could sell all of the silver Silver Cross stuff. One thing about the travel systems is they are bulky and heavy, once the child is big enough not to use the pram or infant part you will find the whole thing is far to heavy just to use as a buggy, we were told this before we bought the 3D by friends who had been through it before. Another advantage of the B-Mobile is its a light as a buggy so no need to replace it after 9 months or so. Im not sure that it converts into a pram though but if you have the infant carrier for the car you wont really need that (we only used the pram part of the 3D about 8 times). We will use the B-Mobile from the start for our next nipper.
The customer service from Britax has been brilliant too we bought the infant seat from one online retailer and the buggy from another. The infant seat has a sunshade which after a while the support tube had popped out so we phoned up and the retailer spoke to Britax who sent another cover straight away. The buggy also had a couple of faults a couple of months into owning it, one of the shoulder pads wasnt stitched properly and had pulled apart a bit so i phoned and complained and while i was phoning i mention that one of the hood clips didnt always stay down, anyway she went away and spoke to Britax who just said send them another buggy which it didn't really warrant. That customer service was enough for us to buy the two car seats from Britax as well. We are really pleased with both the customer service and the quality of the equipment.