Welcome to the forum. This depends on a few factors, such as distance you want to travel, water you're kayaking in (ocean, lake, river, etc.) and tranaport limitations. I like the Revo 16 for speed, sea worthiness and comfort in rough water. The Revo 13 is a great all around boat and may be easier to transport. both are good sailers if you decide to try it. The Outback has a high payload capacity, but is pretty slow in comparison, especially in wind and chop.
I pedal and paddle; as a paddler, you might want to as well. If so, the Revo 16 and 13 will work out best. You cannot edge the 16, but can with the 13 (small point).
As to year, anything newer than 2009 has the current Drive latch mechanism and is best. Chair style seats started in 2015; most people find them more comfortable (and drier), but some prefer the slightly lower center of gravity of the older seat insert.
If you want the MD 180, you want the 2017 and newer models, but since you're not fishing, the previous "GT" or "V-2" fins shouldn't be avoided unless you want to go backwards often! If so, the V-2s came out with the 2009 and the GT in 2015 I think. Personally, I like the GTs best for power and durability. V-2s can be converted to GT but at a cost. In any event, I recommend Turbofins for best performance and a large rudder for best handling. Both of these will up your experience significantly. A cart or set of wheels makes things a lot easier. When looking at a used model, see what accessories are included in the price, as well as the condition of the boat. Learn how to locate and read the serial # so you can verify the manufacturing date, not what the seller tells you. IMO, condition is more important then year though, provided it has those items you want.
Good luck with your search!
