Years ago, dive tables were how everyone dived. At this point, nearly all scuba divers wear a personal dive computer and it makes sense.
The computer tracks your depth, bottom time, ascent rate, and no-decompression limits in real time. Tables can't do that. When you move between depths during a dive, the computer recalculates. A table can't.
Wrist-mount computers are what the majority of divers go for now. They're compact, readable underwater, and you'll use them as a daily watch too. Hose-mounted computers are still around but less divers pick them now.
Budget computers start around $250-400 and do everything most divers requires. They give you depth, bottom time, NDL, dive logging, and usually a basic apnea mode. Stepping up to mid-range gets you air integration, nicer readability, and more mix compatibility.
Something new divers overlook is algorithm differences. Certain models are more cautious dive computers guide than others. A conservative setting gives you shorter no-deco time. Liberal ones allow longer time but at a thinner safety margin. Both work. It's personal preference and your diving background.
Check with the staff at a dive shop who's used various brands first. Good dive stores will give you real-world feedback on what's good and what isn't just marketing. The better Cairns dive stores publish product guides and comparisons online as well