Tables used to be the only option. At this point, nearly all recreational divers dive with a personal dive computer and they should.
A dive computer tracks depth, bottom time, ascent rate, and NDL in real-time. Tables can't do that. When you go shallower mid-dive, a computer adjusts. Tables don't.
Wrist computers are what the majority of divers buy now. They're compact, readable underwater, and you can wear them as a watch as well. Hose-mounted computers are an main page option but fewer divers pick them these days.
Entry-level computers run about $250-400 and cover everything the average diver needs. You get depth tracking, time, no-deco limits, dive logging, and sometimes a basic freedive function. Mid-range includes transmitter compatibility, better screens, and additional nitrox options.
What people overlook is how the computer handles. Certain algorithms are tighter than others. A cautious algorithm results in reduced no-deco time. Looser algorithms give more time but at reduced safety margin. Neither is wrong. It's what you're comfortable with and experience level.
Talk to people at a dive shop who's used a few different brands before buying. Good dive stores will offer real-world feedback on which ones hold up versus what's hype. Most good dive stores put out product guides and rundowns online as well