Back in the day, tables were the only option. These days, the majority of recreational divers dive with a personal dive computer and they should.
A dive computer tracks your depth, time, ascent rate, and no-deco limits in real time. Tables give you a static plan. When you move between depths mid-dive, the computer recalculates. Tables are set before you get in.
Wrist computers are what the majority of divers go for at this point. They're compact, readable underwater, and you'll wear them as a watch between dives. Console computers are still around but less buyers go that way anymore.
Basic computers start around a few hundred dollars and cover everything the average diver requires. more reading They give you depth tracking, time, NDL, dive logging, and often a basic freedive function. The $500-800 range gets you transmitter compatibility, nicer screens, and more nitrox compatibility.
Something people forget is algorithm differences. Certain models are more cautious than others. A tighter setting gives you shorter no-deco time. Liberal ones extend time but with less buffer. It's not right or wrong. It comes down to your style and how experienced you are.
Ask the staff at a dive shop who's used multiple computers first. They'll offer a straight answer on which ones hold up and what isn't marketing. The better Cairns dive stores put out gear reviews and comparisons online too