Welcome to the forum.
There are some other devices coming on to the market now - OBDeleven and others, which are good if you need to run on iOS/Android, or want a less expensive basic system, but if you've got a Windows laptop (even an old one), VCDS (aka VAG-COM) is still top of the heap for 99% of tasks. It does fault codes (auto-scanning the car or manually per module), live data (inc. logging & graphing), guided fault finding (module output tests), coding (long and short), adaption, basic settings, and probably lots that doesn't spring to mind.
There are some really rarified/advanced things it won't do (chiefly related to module flashing), which are basically the preserve of things like VAG-CAN Professional, but pretty much everything else, and certainly everything you'd need for diagnosis and tweaking, it does. It's a bit more expensive than other systems (though the gap shrinks if you take options on the other systems to do things like module coding), but my VCDS paid for itself several times over.
There are counterfeit packages available (cloned lead and cracked software), but I would strongly advise against them - for obvious reasons, but also because with a genuine setup you get better reliability & performance, regular software updates, excellent after-sales (and support the manufacturer in providing their excellent system into the future).
Rob