The trend, you will notice, is that there are bigger differences between one model and year than there is between brands. They all buy compenents from one another.....eg my Honda BF130 has a Mercury gearbox.... I believe some of the 2T Yam V6s had Mercury power heads. The small Mercurys are built by Tohatsu (Nissan ?) I believe the newer Johnson 4 strokes have Suzuki engines under the hood. Old OMC two strokes were bomb proof but you wouldn't want a 2000 one.
Don't touch "Volvo Penta" outboards, you can't get basic service parts for them. (Their inboards are excelent). Don't touch "Chrysler" (Force).
In essence the best thing to do is look for a bargain then do some research into the model and year to look for issues.
Don't go down the route of brand loyalty they all have skeletons in the cupboard.