Most infant car seats will fit into most cars, unless you're looking at bases, then it gets a little bit more complicated, but not that much more so. Unless you have a car which is especially difficult to fit car seats into for some reason, anyway.
IME the infant seats with carry handle are very similar to each other. There is not a lot that can be "wrong" about them, because the safety of them is very simple and difficult to get wrong. It's the toddler stage which is a much bigger headache TBH!
Do you want one which is compatible with a pushchair? If you do that can help narrow down your choice quite a lot. I found it easier to choose a pushchair first and then choose a car seat from the ones which were compatible, because it seemed like there were more differences between pushchairs so that seemed much easier to choose from. However I would be wary of ending up with the ubiquitous Maxi Cosi! There is nothing wrong with Maxi Cosi, they are excellent seats, but they are also not the only seat on the market despite how some sales people act about them.
The system IS really complicated but happy to help if I can. I've been looking at car seats for over 10 years and I find the whole topic weirdly fascinating XD
Other questions I'd look at -
Are you on a low budget? Don't mind spending out a bit more for better features? Feel no expense spared for the best is the best policy?
Do you plan to have more DC in future or is this baby likely to be your only one?
Are you interested in the possibility of a base to click the seat easily into your car?
Are you worried about the baby being too upright in a car seat? You can get some with padding which make the seat a bit flatter for newborns, and you can also get some (more pricey) ones which are totally/true lie-flat which means you don't need to worry about car seat time limits.