JPM vs William Blair vs Aberdeen

I received an offer from the three firms- middle market commercial banking in JP Morgan, sell-side equity research in William Blair, and a rotational investments program in Aberdeen Standard Investments. My long term goal as of now is to work as a research analyst in asset management, hedge fund, or as an investment bank, but I'm open to other options as well. I've heard people advocating buy-side as opposed to sell-side, but I'm quite torn as William Blair has a good brand name in the US. On the other hand, Aberdeen Standard Investments is a big asset manager in UK but not really well-known in US (where I'll be working) and has a decreasing trajectory after their merger. Appreciate all the help!