So the art in the MgT books is... questionable. It's the least of my concerns. I buy my game books for content, not pretty pictures. Even if a book is ugly, i'll still buy it if the content seems useful and interesting to me. Though, I would choose no art over bad art had I the choice. The stuff in Agent is revolting.
Remember the old b&w d&d art? That stuff was wretched, too.
I'll agree the Pathfinder books are very pretty, i like my 4e D&D ones too, but sadly, I still would prefer no art. It's largely due in part to my players lacking the imagination to create their own image or version of something. So, if there's a picture in a book of something, every one you encounter looks and feels the same. Subsequent, though, if there's a picture for everything else, but one thing, that one thing will automatically become like something else. This is how Katana's functioned and looked like longswords in one game, but I'll spare you from the pain.
Art is nice. It's a tool to help inspire us as players and GMs to create awesome stories. I have a crazy group in their nice little box. I'm just unlucky like that.
Now, getting back on topic. When I made the plunge into MgT, I started with the core book, high guard, mercenary, merchant prince and Spica's first career book. All that covered hat my group was gonna be dealing with. I'd like to say I fleshed my collection out over time, but I'm one if those crazy bastards that goes all-or-nothing when deciding to get into a system, so I buy my books in massive splurges. I almost finished my collection in two more shopping trips. I did not buy animals, scouts, library data, that big character book( 1000 and something?) and the 2 vehicle books. Also, the only 3I book I have is Starports.