I left Horizon a couple of years ago, but at the time any Horizon Dispatcher who applied was offered an opportunity to interview at Alaska. Alaska hired 3 Horizon Dispatchers in that time frame.
Several of our Dispatchers left other airlines to come to Horizon. They were Pacific Northwest natives that wanted to get back home.
Before the move to SEA there was almost no turnover in Dispatch. People took jobs at Horizon because they wanted to live in PDX, and they stayed. 20 year Dispatchers were the norm, not the exception. They didn't apply to other, larger carriers because they wanted to stay in PDX. The move to SEA changed that.
Horizon is a fine airline, and I would rate their Dispatchers as competent and qualified as any in the profession. That said, I wouldn't leave another regional for Horizon in the hopes that I might get hired by Alaska. That's a poor career strategy, in my opinion. Take a job, or don't, based on its own merits, not because it might open a door in the nebulous future.