I have both and really like both. If you’re looking for something that feels a bit more like a strategy game I would go for Welcome To whereas if you’re looking for a pretty box that’s great fun maybe go for Railroad Ink. Initially Railroad Ink seems more accessible but it’s actually pretty tricky for some people to grasp the most efficient way of laying out your network. However, it’s definitely an easier one to get the concept quickly. Also if you’re looking to play a lot then Railroad Ink’s re-usable boards will hold out for longer than Welcome To’s sheets (although you might need to replace the pens at some point)
Welcome To feels like there’s a lot more variety in the “core” puzzle - you can either focus on City Plans or decide to try and get all the pools or maybe build a lot of parks. It also has a bigger sense of progression and mastery. I’ve only played 3 games but my score has gone up from 60ish to 103. It’s got a great puzzle and it will take a long time to figure out how to balance all of the different abilities. It also comes with achievements!
Railroad Ink has stayed really fun after a dozen or so plays, and I haven’t tried the expansion dice yet! Scores seem to vary less and it can be less predictable. My Railroad Ink score has varied between the mid-40s to the mid-50s with one lucky 63 as my high score. It definitely has more of a push-your-luck feel where you can set up your networks to rely on the dice doing exactly what you need in the final turn, which is always tense and leads to stronger emotions. It feels like you’ve got slightly less control over the game since the dice don’t offer the same reliability as Welcome To’s deck.
Railroad Ink is a game of ups and downs that are often experienced together whenever someone rolls all corners . Welcome To is more a game of long term planning and frustration at your own mistakes (although that also applies to both). Welcome To tends to also have different strategies arise, whereas Railroad Ink’s strategies are less readable and interesting to compare.
Welcome To has the race to achieve city plans which adds some player interaction whereas Railroad Ink is a purely solitaire game - you all use the same dice and see who can use them best - so if you’re desperate for some player interaction then Welcome To is probably the best candidate. I find it easier to get Railroad Ink to the table (or wherever, it’s super portable, whereas Welcome To not so much) but I’m also excited to get better at the Welcome To puzzle.
I really love both, really depends on which aspects of them you’re interested in