I agree with some of the points above:
1) Make a list of things that are important to you and get the buggy which comes closest.
2) Think of the practicalities of life with the buggy, not just how pretty it looks - things like, will it fit in the boot of your car (we have a Ford Fiesta and half the buggies out there won't go in the boot without having to arrange it all very carefully) and can you lift it easily once it's folded down (we were lent a very heavy one which, whilst free, was a real pain to get in and out of the boot).
3) For me, being able to have a rear facing and forward facing seat unit was very important, so I could see baby for as long as possible. I guess, once he's a bit older, he'll want to face outward, but in the first few months I wanted to be able to keep an eye on him.
4) Make sure the seat unit is suitable from birth onwards if that's what you need - some don't lie entirely flat, which means you'll have to splash out on a carrycot (in my view, an unneccessary expense) or use the car seat all the time until baby can sit up.
5) Try out the buggy as much as possible in a shop, even if you're going to end up buying online - if you buy something you've not tried out, who knows if it'll suit you/baby.
We've ended up with a Britax B-Smart 3 wheeler (the 2011 version) which is working out really well. Don't be put off by the negative reviews, they've made the straps a lot longer (although they're still snug when used with the footmuff).