As mentioned, some of the ones that collectors are always on the look for are what are called V and EX cards, which are full art displays of the featured Pokemon
To ensure the authenticity of an error, purchase an example already certified by CGC Trading Cards, as every card graded by the CGC Trading Cards experts is guaranteed to be authentic and unaltered.
Heres a full breakdown: Beginner Solo Battle First Time Rewards : 2 Pack Hourglass, 1 Promo Pack B Series Vol 5, 1 Shop Ticket, and 25x EXP
An especially flavorful alternative would be a wishboard of just three cards
Blue works well with the themes of Kaladesh and is the color that contributes to some of the best decks in Standard
Its also one half of a combo that could easily fit in a Petitioners deck