I think it's most important to train at a place where you will be happy. Prioritize that above all else. Really...I feel like people don't believe this. This might mean staying close to home but probably depends what stage of life you're in and where home is. Personally, I was young enough for undergrad and med school that I would have traveled anywhere. As a fellow, I was married and starting a family so things like being close to family, cost of a comfortable living, etc. become important.
Reputation of where you train is probably not as big a deal in our field as it is in some. There aren't really poorly regarded community programs or anything like that in A/I. Pretty much all fellowships are at academic centers or solid academic/community hybrids like Scripps, Mayo, or national jewish. Among those, some are more clinical and some are more academic. Some programs that don't have fancy names actually offer solid, balanced clinical exposure and teach better "real world" allergy. Some academic power houses prioritize research, skew peds vs adults, or prioritize hardcore clinical immuno above others. If you wanted to stay in academics, then go for pedigree and research exposure. If you want to do private practice, prioritize clinical training.
As far as training where you want to eventually work, that's hard to say. If academics is your goal, then absolutely you are more likely to stay on at the institution where you train since you will be starting projects and working with mentors while there. If PP is the goal, it's probably not as important. I trained in a totally different state from where I currently practice. I did grow up where I practice though, so had plenty of ties to the area. If you know where you want to work, you can start applying for jobs early in fellowship. I think practices are looking for the right fit more than anything else. Sure, if you trained at a well known place, that has brand recognition... but I don't think anyone is passing someone up simply because they trained at University of X vs U of Y. Local connections can help if you're a good fellow because there's a good chance docs at your institution know docs in the community. ....but don't be surprised how locked in a bubble the academics people are -- some of them have never been in private practice, know very little about it, and most of the docs they a/w are also in academics. In PP, fit matters and lots of the BS that got you into med school, residency, and fellowship may not matter as much. It's a business...we want good clinical outcomes, happy patients, no drama, and efficient work flow. The partners in our practice come from various programs around the country and other groups in town are similar. There is one group in town that has the majority of its docs from the same training program but I don't know if that's coincidence or not. It also probably depends where you want to practice. If you want to practice in Denver, you've got like 7 fellows a year graduating in the area, might be tougher for an outsider than other locations. If you want to practice in a city that graduates like one fellow per year, probably less important.
