Back in the day, tables were the standard. Now, most recreational divers use a dive computer and they should.
The computer calculates depth, time, speed of ascent, and NDL in real time. Tables can't do that. When you go shallower during a dive, it updates. more help Tables are set before you get in.
Wrist computers are what the majority of divers buy now. These are small enough, readable underwater, and you can wear them as a regular watch as well. Hose-mounted models are available but less divers pick them now.
Basic computers run about a few hundred dollars and do everything the average diver would need. They give you depth, dive time, NDL, dive logging, and usually a simple freedive function. Stepping up to mid-range gets you wireless air monitoring, nicer readability, and more mix compatibility.
What buyers don't think about is conservatism settings. Certain computers are more cautious than others. A cautious algorithm gives you reduced NDL. More aggressive ones give more time but at a thinner buffer. Neither is wrong. It just what you're comfortable with and experience level.
Check with people at a dive shop who dives with various models before buying. Good dive stores will offer a straight answer on what's good and what's marketing. Decent dive shops have gear reviews and honest reviews on their sites too