I say go new with a stern; but despite so many new sterns on the market, your options are limited. Here they are and gives you something to think about:
Ghostbusters (GB): I say stay away for 2 reasons. 1. Code issues - game has good rules and is fun overall but its still the newest game off the line for stern and has a long way to go code-wise before it's really complete. 2. Its a harder playing game, lots of drains, airballs, design quirkiness which could lead to a frustrating first pin.
Spiderman Vault (SMVE): Honestly, this is a great first pin buy if you dont mind the pricetag. Make sure you get a newly built SMVE though (from this month or last), as the first run Spidermans have been known to have playfield quality (ghosting) issues. And only get this if you like the theme. Check out some youtube videos and make sure you enjoy the call outs and such. But overall, it has great first pin owner appeal to it - great flow, great toys, great rules.
Game of Thrones (GOT): Stay away from LE/Prem if you go this title, at least until they put out some worthy code that supports the upper playfield. Dont get me wrong, the LE/Prem is a great playing game and the mini playfield is great - but the rules surrounding the mini playfield do not match the rest of the games ruleset. I even say stay away from the pro too until code gets some long overdo attention it deserves. Also, this is a players game - its not your A-typical type of game, the ruleset is built around combos and multipliers, there isnt much story telling or adventure-quest like aspects going on in this pin. Its a scoring, flowfest, combo-fest, multiplier-fest style game. So until you understand those types of games or appreciate them - i'd stay clear of GOT.
Kiss: Stay away from this until code is updated and it gets the stamp of proven approval with the pinside player fan base.
WWE: Yea, dont touch this game or think about it
Walking Dead (TWD): Great ruleset, great pin. But its HARD! another one i would stay clear from unless you know what you're getting yourself into. You'll need someone's aftermarket sound code if you do get this game. The rules and code on this pin is one of the best - but it comes at a price; while the shots are tough and satisfying, the game is hard - both ruleswise and design wise. Still one of my favorites though.
Star Trek (ST): Wouldnt be a bad first pin to own. The flow, design, and layout is great. The warp ramp is one of the best shots to shoot for continuously over and over in all of pinball. Sounds, music, and effects are all top notch. I prefer the LE over any other model but thats pricey. One red flag on this pin is that the ruleset isnt very noob friendly and seems to only satisfy 50% of the pinside population here. So without knowing what type of ruleset pins you prefer, ST may not be good for you for that reason only.
Metallica (MET): This is a great first pin if you like the theme. Either version is great (pro/prem/LE). This is typically a great pin for new pinheads as it has a simple layout and great surrounding code. For more experienced players, the rules can become very grindy which could be a turn off in the long run. But overall, if youre a fan of the band, metallica is a great pin to own. Highly Recommend.
Batman 66 (BM66): Yea, stay way clear of this one until at least next summer when we finally see gameplay and code.
Overall Summary: I recommend MET, then TWD if you like brutal gameplay, then GOT PRO (if you like scoring based games rather than quest games), then ST, then GB
Another game to think about is MMR (Medieval Madness Remake) - if it's within your budget.
Also, aftermarket mods - you'll want at least a shaker motor (included with SMVE) and a polk audio subwoofer https://pinside.com/pinball/forum/topic/polk-audio-psw10-10-powered-subwoofer-9999#post-3448121
Good luck and congrats on your potential first pin purchase