I spent half my childhood in Harrisburg (the other half in the Philly suburbs). I only recently finally moved out of Harrisburg this past year for Lancaster. Harrisburg really wasn't a good place to live. Incredibly boring city, even for being the capitol. Many folks who work in the city of Harrisburg don't even live there and they leave the moment their shifts are over so the city becomes a ghost town after 5pm. High crime for an incredibly small population of only around 50,000. Horribly designed and outdated traffic signals, means that every red light you hit will be a good 5 minute punishment light. What should take you 20 minutes to get somewhere turns into 35 minutes just because of how outdated the traffic lights are. I know that doesn't sound like a big deal, but it contributes towards the cluttered amount of traffic for a city that really shouldn't have traffic issues. But yeah Harrisburg has largely deteriorated and most folks are miserable. It's your typical rust belt city that was once a prosperous place but those days are long gone.

I think Lancaster would be your best bet from all those choices. Unlike Harrisburg, there is a lot of community involvement. It has a booming tourist economy in the summer that brings attractions to the city. Many businesses are up and coming in the area. I moved to Lancaster mostly for that reason. The company I work for is based out of Erie but is trying to build a client base in Lancaster. Lancaster also has more diversity than Harrisburg (the city at least). I like to describe Harrisburg as a Crayola box with only 2 different crayons. Lancaster city has all kinds of people though. Very large Hispanic population, but I've met a lot of people from Nigeria, the middle east and the Philippines. Lancaster has more age diversity as well. A lot more people in their 20s-30s than I ever saw in Harrisburg. But in terms of what you're looking for OP. Lancaster has much lower crime than Harrisburg. It's practically a night and day difference. Made even more interesting because Lancaster and Harrisburg half around the same population. Lancaster city has decent walkability and public transit. You'll run into issues with that if you decide to leave the city where things become very rural very fast. I will give Harrisburg some credit in that regard in that it is a more walkable city. Lancaster has significant more economic growth than Harrisburg by far.

edit: If the online presence is anything to go off either, check out the Harrisburg and Lancaster subreddits and compare them. I see events, pictures and questions posted all the time on the Lancaster subreddit. But the Harrisburg subreddit is practically dead.

As for the other cities, I've never lived there but I can speak on how they were when I visited. York seemed depressing. Very rundown city. I saw a lot of homes that just weren't cared for and a lot of trash. I'm sure there are nice parts, but I didn't really travel through them. I've been to Reading a few times. Noticed a lot of warehouses and industry. Lots of tractor trailers. Wasn't as trashy as York, but it just didn't seem particularly interesting. It feels very much like a rust belt city. I can't say much on Lebanon, but anyone I've talked to who has lived there has had some crazy story to tell. Whether it's some racist asshat or drug related. I wouldn't want to live there regardless.