I have a list of workhorse decks. These are decks that are always reliable ( for me); some of them I would never have imagined being a workhorse deck. Apart from my Blue Box RWS and Albano Waite these decks are:
Cosmic Tarot
Book of Azathoth Tarot
Royal Fez Moroccan
Alchemical Tarot Renewed 4th Edition
Bonefire Tarot
Deck of the Bastard
These are either Thoth influenced (Cosmic), RWS or a bit of both (Azathoth).
1880 Soprafino/Ancient Italian, Zirkus Magi, and...oddly enough, The Zombie Tarot. Other decks might be prettier, have more general credibility, or be new and exciting, but these three will work for me on all but the worst days.
Decks I reach for constantly are RWS, Circo, Fantastic Menagerie, Anna K and, it's fairly new to me but I see it becoming a workhorse, the World Spirit.
Right now, just the Wild Unknown. I define "workhorse" as a deck that has high stamina and good readability, while also being reliable to me and generally agreeable to other querents. I've had the WU for over a year while most of my other decks are half at most, so it'll take me a while to see which of my newer decks will fit the bill.