The MS 280 is no longer manufactured. It was a light duty, 54.68 CC saw. The MS 291 is the current model, and is a 55.5 CC "Farm and Ranch" saw.
Personally, in a 50cc Stihl saw, I'd get the MS261 as it has more horsepower and weighs less than the MS 291. However, like all professional saws, it comes with an elevated price tag - but, you get what you pay for.
Jonsered saws are Husqvarna saws in red with a few features, like the handle, that are different. Stihl, Husqvarna, Jonsered, Dolmar / Makita, or Echo - all good saws. Best power / weight ratio will be found in the professional level saws from Husqvarna, Jonsered, and Stihl.
I buy Stihl because the dealer is 7 miles from house and the Husqvarna dealer is 25 miles. My local Jonsered dealer is Tractor Supply. They don't have parts/service and their chainsaw "experts" consist of a rotating cast of shelf stockers.
Buy whatever brand you want - but, my advice is to look past the color or manufacturer and find the best total package that includes the availability of parts and service.