My first deck was RWS, since so many others are based on or closely related to it, conceptually. It happened to come with a Thoth deck, which I have only recently opened to thumb through.
I had also picked up a BOTA deck for study, along with learning the intricacies of the symbolism.
And I have since been gifted another close variation on the RWS deck.
But since I've started studying the occultic correspondences with the tarot deck, I've picked up the Golden Dawn deck ... along with two books on the subject of occult symbolism in the tarot.
My opinion on wanting the two decks: Buy one. Save up a bit, and buy the other. You may find one works for one application better than the other.