Back in the day, tables were the standard. These days, the majority of divers dive with a wrist-mount computer and for good reason.
A dive computer calculates depth, bottom time, speed of ascent, and NDL in real time. Dive tables are a fixed calculation. When you move between depths during a dive, a computer adjusts. Tables don't.
Wrist-mount computers are the most common buy these days. These are small enough, easy to read, and you'll use them as a watch as well. Hose-mounted models are available but less buyers choose them anymore.
Entry-level computers start around $250-400 and do everything a recreational diver would need. They give you depth tracking, bottom time, no-deco limits, a logbook, and sometimes a simple freediving mode. The $500-800 continue reading range gets you transmitter compatibility, nicer screens, and more nitrox options.
Something people don't think about is algorithm differences. Certain computers are tighter than others. A conservative algorithm gives you less NDL. More aggressive ones extend time but at reduced safety margin. It's not right or wrong. It comes down to your style and your diving background.
Ask the staff at a dive shop who dives with a few different models before buying. Staff will have honest opinions on which ones hold up and what isn't marketing. Most good dive stores publish gear reviews and comparisons on their websites too