What part of the Harrisburg region - where will you be living? Many of the stables on the linked list are east of Harrisburg; if you'll be south or west, there are other possible stables, in addition to the ones on the list.
Hidden Echo Farm, Carlisle, PA -- home of JC palomino sire Canadian Kid (1990 - 2013) & AQHA sire Lark's Favorite, son of Rugged Lark.
Jill Shull/Equi-comp located in Carlisle Springs. She goes to Ocala in the winter for a few weeks, Vermont and HITS in the summer and mostly other A-AA shows in the area. There is a very nice and supportive group of people in this barn. Mostly AA/AO riders and just a couple of teen riders.
Chris Gemmil/Woodberry Farm in York. Her barn shows locally thoughout the winter, also shows at the bigger shows in MD and VA throughout the year. Another group of very nice people there with a mix of adults and children.
Rick McGrath/Central Pennsylvania Equine Center out towards Middletown (I think). Fl in the winter and VT and HITS in the summer. I am not familiar with his clients.
There are several other good options in the area, it all depends on what your goals are. Please PM me if you want to know more about them.
As far as the best care and full service, I would look at Halcyon Farm in Dillsburg. Barb Kohr is really invested in her animals and your horse would receive the best care in the area. Her phone is 717-503-6622. I went there myself after my barn changed from full service to a coop and I have never been happier. Won't go anywhere else. I know all of the trainers that have previously mentioned (looked into all of them when the change happened at my barn) and the care is not the same anywhere else. PM me if you want more information.
There are quite a few nice barns in this area with different focuses. Please feel free to call me if you like and with more detail, I could make better recommendations. Our phone number is on our website.