Financeability is important. Banks have little interest in small startups unless most of the capital is already in place as equity and even then they are likely to require plenty of collateral. They may insist on a second mortgage on your home. Expect to get your initial capital from savings, family sources and partners. A going concern, on the other hand, is more creditworthy.
Lenders are familiar with management buyouts.
If you need partners, the other key employees may welcome the opportunity to buy in. In addition, all entrepreneurs must eventually sell and retire, so such sellers, with relatively little negotiating room, are likely to be more flexible. And, a going concern requires less capital and embodies less risk. Finally, there is little question about valuation, since you've been inside and perhaps had access to the books for several years. Valuation and financing can be troublesome in the case of a purchase by an outsider.