If you're new, it will be tempting to overthink your choice. Asking people who have already made a choice is likely to result in too much information, some of which will be biased in favour of the decisions those people made for themselves. That's how internet forums work.
The right choice for you will depend on many variables, and it will change as you gain experience.
Single speeds and fixed are good fun. They appeal to me for their simplicity. They require slightly less maintenance, but the maintenance is not onerous on a geared bike.
On any bike, you will need to clean and lubricate the chain. On a single speed or fixed, you need to adjust the chain tension. On a derailleur bike, the gear mechanism takes up the slack automatically.
Hub gears have their fans and detractors. They require minimal maintenance — less than derailleur — and are more versatile than a single speed. Many people dislike them, and many of those people have never used them.
On any bike, you will need to adjust your brakes occasionally.
Yes, some people ride without brakes on
fixed. Some people will say that is dangerous; others will say it is a skill that takes time to learn and practise. In some jurisdictions it is illegal. Be that as it may, it is not an option on single speed or geared.
Other than that, for most people, most of the time, bike maintenance is minimal. Some people here are talking about sealed bearings being low maintenance. Yes they are, but back in the day I rode many thousands of miles on bikes now considered "old tech" with traditional bearings and very seldom had to do any bearing maintenance.
Remember that the bike used to be the poor man's transport: simple, robust, no fuss. There is nothing on a bike that is difficult to maintain. Apart from the chain, you can go for weeks or months on any bike without having to do more than a quick check that nothing is loose or damaged, and maybe turning the barrel adjuster on your brakes or gears.
Things to consider:
Fit. Get a bike that is comfortable. It is easier to make a small bike slightly bigger (longer seat post, longer stem) than it is to make a big bike smaller, but you need one that is comfortable.
Bars. These can be change, but if you change the basic style (from flat to drop or vice versa) you will also need to change the brake levers. Drop bars are versatile and are generally better for longer and faster rides, but flat bars can be more comfortable and you sit more upright which is good for seeing what's happening ahead in busy traffic.
Tyres: somewhere around 25mm to 28mm is a good balance of speed and comfort. 23mm tyres can give a very firm ride and are more prone to punctures. Any sort of knobbles will make a real difference to how much effort it takes to pedal.
Budget. Buy one that is very cheap and you will be disappointed. Buy one that is very expensive and you will probably not get the benefit because as a beginner you may make a bad choice. Go for something expensive enough to be decent quality, but don't pay the extra for fancy features. See what you like and dislike about it then plan for a better bike later. At UK prices, if I were buying a first bike, I might be looking in the £450 to £600 bracket.
Upgrades. Whatever you buy chances are you will soon upgrade the seat and pedals. These are an investment as you have the option to transfer them to your next bike if you upgrade a year or two later.
Carrying capacity. If you're commuting, how will you carry your lunch, your briefcase, phone, tablet, or whatever? A pure road bike with no mudguards/fenders will give you a wet backside in the rain, and will oblige you to carry your luggage on your back, which is sweaty. Something more practical (mudguards/fenders and rack and panniers) will be heavier and a bit more stodgy to ride.
Lights: if you plan to commute all year round, will you be riding in the dark? If so, get some decent lights and decide where they will fit on the style of bike you've chosen.
Clothes and shoes. You can ride a bicycle in anything, but it is more comfortable to ride in proper cycling clothes and shoes. However, if you're commuting, how will you transport your work clothes? If you commute in your work clothes, you will need to adjust your riding accordingly to avoid arriving sweaty.
Security. Where will you leave it, how will you lock it, and how will you carry the lock? Depressing rule of thumb: if you knock a pound off the weight of your bike, add 1.5 pounds to the weight of your lock...
For the length of rides you've described, a single speed or fixed would not be inappropriate. Plenty of people ride further on this type of bike. Whether it is the best choice for you is for you to decide. Every bike is a compromise.