Back in the day, tables were the standard. At this point, the majority of recreational divers use a dive computer and they should.
The computer tracks your depth, bottom time, speed of ascent, and NDL in the moment. Dive tables are a fixed calculation. If you change depth partway through, the computer recalculates. Tables are set before you get in.
Watch-style computers are the most common buy these days. They're compact, easy to read, and you can wear them as a regular watch too. Hose-mounted computers are available but less people pick them these days.
Entry-level computers start around $300-odd and handle everything the average diver needs. Features include depth, time, NDL, a logbook, and sometimes a simple apnea mode. Mid-range adds air continue reading integration, nicer displays, and extra nitrox options.
What new divers don't think about is conservatism settings. Some computers are tighter than others. A cautious setting gives you shorter NDL. More aggressive ones allow longer time but at a thinner buffer. Neither is wrong. It just what you're comfortable with and your diving background.
Worth talking to the staff at a dive shop who uses multiple models before buying. They'll have real-world feedback on what works and what's hype. The better Cairns dive stores publish buying guides and rundowns on their sites too