Yes the options can be overwhelming! IMO you're right to look at it now. Then you can keep an eye out for offers before you have to buy quickly.
Are you planning to get a pushchair you can click the car seat into? If so, I would choose your pushchair first. That massively narrows down your options for car seats and you'll have a smaller pool to choose from, making the research easier.
If not, or if that would be a bonus rather than important, here's an overview of options, feel free to ask of course if you need more info.
Basic infant carry seat - This is the most popular choice. Also known as a Group 0+ seat. They are suitable until about 12-18 months depending on the size of your baby and have a maximum weight of 13kg, but are designed that babies outgrow in length before weight. Always rear facing, and they come with a handle, so you can move the whole seat with the child in. If you would like to, you can get a base to click the seat into your car, otherwise they strap in using the seatbelt. A useful option for two cars is to get one seat with two bases. These car seats normally are possible to click onto a pushchair, though that's not required of course.
Sometimes you'll see these seats being sold as "i-size" which is a new regulation and means they have passed higher safety testing. These will be rated by length instead of weight, but tend to fit until around 12-18 months again. Be aware that if you buy an i-size seat you MUST NOT move to forward facing until your baby is at least 15 months old. That means if your baby outgrows the seat before 15 months (which tends to be big babies), you'll need to buy another seat which can rear face.
On bases - a couple of the companies offer family or modular bases which promise that you can use one base for several of their car seats. This sounds very useful until you consider that most Group 1 seats (1-3 years generally) do not need a base, and so the manufacturers are doing a clever little marketing trick locking you into assuming you've got to upgrade to their next stage model, since you already have the base for it. If you want to research Group 1 seats already and have decided you definitely want this company's seat, plus it's unlikely you'll have a second child needing to use the base with the infant seat, it might be a good option. Otherwise, I would not bother with any modular bases, or at least, don't buy them specifically for future compatibility reasons - just assess them on price/practicality as a base for the infant seat you're looking at.
Multi-stage seats - these options have become much more popular in recent years and it's now common to be able to buy seats which span across multiple car seat groups (weight categories), from Group 0+ for newborns, right up to Group 3 which is a booster without a backrest. I would suggest to you that the most beneficial to look at is the selection of Group 0+/1 seats which cover from birth until around 3-4 years old. This includes convertible seats, extended rearfacing seats, and 360 spin seats. All of these seats are designed to stay in the car and tend to be more cumbersome to move around, so you would probably want two for two cars. Again, consider the possibility of a second child potentially needing the same seat at the same time meaning you may end up with four, although you could upgrade the elder to a larger type seat instead. Now I'll split them up.
Convertible seats - these are rear facing until the end of Group 0 or 0+ and then forward facing. Beware of cheap ones where the RF limit is something like 9 or 10 kilos, as these will force you to forward face earlier than is safe. Although it is legal in a group type seat to forward face from 9kg onwards, this is strongly not recommended as your baby's neck would not be strong enough to support their large head even in a moderate crash. It's recommended to rear face until at least 15 months, as this passes the most dangerous point, but it's always safer to rear face for longer. A RF limit to 13kg will get you to about 2 years. But TBH, this style of convertible seat is outdated - there are cheaper and better designed ERF seats on the market which give you the choice.
ERF or Extended Rearfacing Seats - These cover groups 0+/1 or are increasingly i-size compliant, meaning they can usually be used until your child is around 104cm which is roughly when they grow out of age 3-4 in clothing tops. (Group 1 harnesses are usually this size, too.) Ask your close relatives what age their children have. The benefit of these seats is that the child can remain rearfacing for the lifespan of the seat which is a safer option. Additionally, they have the option of facing forwards from 9kg (for a group based seat) or 15 months (for an i-size seat).
360 spin seats - Sometimes ERF, sometimes just convertible. The selling point is of course that you can turn the child towards the car door which makes it easier to get them in and out and adjust straps.
"All in one" seats which cover from birth up to group 2 or 3 - I do not personally think these are worth it as for the difference in price you can buy a decent high backed booster later on anyway. The exception is the Diono Radian 5 which can genuinely be used from birth until no longer needing a seat, and includes longer harnessing, if that is something you're interested in (which you probably have no idea yet.) My advice - get an infant carry seat or a good 0+/1 seat for now, worry about this question later.
Isofix or not? - Isofix fitting removes user error when fitting and is convenient. It's no safer than a properly fitted seatbelt fit, however you'd have to be confident that your seatbelt fitting is spot on. i-size seats all use isofix.
Saving money: If you are looking at the low end of the market price wise, the only two brands worth looking at are Britax and Joie. Joie in particular is excellent for putting premium features in a low priced seat, and have made ERF affordable. There are lots of cheap seats on the market and I wouldn't trust their safety. Joie has excellent records. For mid range, IMO, Maxi-Cosi overprice for what they offer. They trade on their name and the fact they are well known. Other brands are available. It's worth asking a shop assistant which other car seats are compatible with maxi cosi adapters - for example, Cybex are. The really expensive seats tend to have features which are not safety related - don't think by buying the most expensive seat, you're getting the safest. Once you get past the mid-range, you are paying for convenience, comfort, or design.
Fitting - most of the big manufacturers will have a "fit finder" on their website, so you can check the fit for your car. However, for most modern cars car seat fitting is no problem. This is more of a cursory check.
Good luck! Hopefully that didn't just confuse you more