Tables used to be the only option. These days, most divers use a dive computer and for good reason.
A dive computer monitors your depth, bottom time, ascent rate, and no-deco limits in the moment. Tables give you a static read full report plan. If you change depth during a dive, it updates. Tables don't.
Wrist-mount computers are the most common go for these days. These are compact, easy to read, and you can wear them as a regular watch between dives. Hose-mounted models are available but not as many divers pick them now.
Budget computers start around $300-odd and handle everything most divers requires. You get depth, dive time, no-deco limits, dive logging, and sometimes an entry-level freediving mode. Mid-range includes air integration, better screens, and more mix modes.
The one thing people don't think about is algorithm differences. Some models are tighter than others. A tighter algorithm means less no-deco time. More aggressive settings extend bottom time but at a thinner safety margin. Neither is wrong. It just personal preference and experience level.
Talk to people at a local dive store who dives with a few different computers before buying. They'll give you real-world feedback on what's good and what isn't just marketing. The better Cairns dive stores publish gear reviews and rundowns on their websites as well