Back in the day, tables were the standard. At this best dive computers point, the majority of recreational divers wear a dive computer and they should.
Your computer monitors depth, time, ascent rate, and no-deco limits in the moment. Tables give you a static plan. If you move between depths during a dive, a computer adjusts. Tables are set before you get in.
Wrist computers are the most common go for at this point. These are small enough, easy to read, and you can wear them as a watch too. Console models are available but less buyers choose them now.
Entry-level computers start around a few hundred dollars and do everything the average diver requires. They give you depth tracking, dive time, no-deco limits, log function, and often an entry-level freediving mode. Mid-range includes air integration, better displays, and extra gas modes.
Something people forget is how the computer handles. Some algorithms are more conservative than others. A tighter computer means reduced bottom time. Liberal settings give more bottom time but with less safety margin. It's not right or wrong. It comes down to what you're comfortable with and your diving background.
Worth talking to people at a dive shop who uses various computers before buying. Staff will give you a straight answer on what's good and what isn't just marketing. Most good dive stores put out gear reviews and comparisons on their sites too