Thanks - it is a nice little lineup!
To me, the way I ride them, they are very different. My 8'10" Speeed is fast, stable, easy to surf, but you have to get on the tail if you want to do fun turns - and I love fun turns!
The Minion is a foot shorter (and a little less volume) and has very round rails. It is far less stable in every axis. So, if it was fairly clean, thigh-high or bigger waves, and not very crowded (so I could make sure I was in the right spot to catch the wave and not overly stressed if I missed a wave) then I would take the Minion every time. I love the way it turns and I love rolling up and down the wave as you race along the wave.
But so often there is wind, slop and small waves, so I use the Speeed much more.
From now on I will have a challenge deciding whether to take the Flow or the Minion. If it is small - the Speeed will go. But if there is a bit of size I think the Flow will go - unless it is very clean, then the Minion will go. (I can manage on the Minion if it is choppy but I occasionally miss waves because I bobble at the wrong time and can't power-paddle on to the wave.)
(I am 90 kg, 6'3" and 54)