Which Tarot Deck is Best for a Beginner?
The best way to answer your question is to understand what Tarot is (in a traditional sense): it is a series of images which feature symbols that have relevant meaning for human life and existence.
Let us look at that statement again, a little closer: Tarot is a series of images which feature symbols that have relevant meaning for human life and existence.
Therefore, when we consider Tarot cards---especially for professional readings and consultations---we need cards that will show images that are symbols with relevant meanings.
Tarot decks can be divided into several broad categories:
Tarot imagery developed from earlier card deck imagery which in turn developed from religious and spiritual iconography of the medieval and ancient world.
The most popular, and arguably the best deck for professional consultations, is the "Rider-Waite-Smith" or RWS deck, because of its heavy usage of traditional iconography and classical symbolism. Each of the 78 cards features multi-level meanings when both upright and reversed.
Even small details such as color choice, elemental connections, numerological associations, and astrological symbols are included in the RWS and other traditional decks.
Because of the sheer depth of symbolism in these traditional decks, they are highly recommended for both a beginning Tarot reader who wants to take Tarot seriously (instead of for pure entertainment) and who wants to be able to provide high-quality, professional consultations to clients.
These are Tarot decks which are based off of the RWS and other traditional decks to varying degrees.
These decks may feature art that may be more "beautiful" to the eye, but lacks the fullest symbolism and meaning of the original decks.
Examples of a deck of this nature are the Arthurian Tarot, the Wildwood Tarot, and countless others, all to varying degrees.
These are Tarot decks which are only loosely based off of traditional Tarot decks, and often feature extremely bizarre imagery (which is largely outright meaningless to anyone besides the deck's creator).
Although these decks can be exceptionally pretty, they often are unusable for professional consultations because the depth of meaning is shallow and the possible combinations of psychological situations and events are limited.
Many "Oracle decks" fall into this category to varying degrees, and so do many popular decks such as the Wild Unknown Tarot.
Some of these art decks are better than others, but none can match the depth of the traditional decks because their meanings tend to be influenced, in one way or the other, by the artist's own interpretations, beliefs, and values (which are, sometimes, neither highly spiritual nor of psychologically-sound character).
ADVICE FOR A BEGINNER
What should you do, then, when seeking a first deck?
Decide what you want to do:
Do you want to own a Tarot deck just for fun and light entertainment, or just because you like the look of it?
Get an art deck that you enjoy.
Do you want to learn Tarot at a semi-professional level, and maybe read for others semi-seriously for payment?
Get at least a traditional-inspired deck.
Do you want to learn Tarot at a professional level, and provide serious consultation services for others?
Get a traditional deck. Then, spend the many hours necessary to learn the traditional symbolism, understand Tarot at a deep level, analyze the psychological and spiritual connections of each card, etc.
This is a long path but is extremely worthwhile if you enjoy providing consultation services as a business and lifestyle.