I like both. For example, the 890 Duke R, while not a slow bike, is almost magical in that it can turn in amazing ways. The brakes are monstrous and it is very light. So flogging her is great fun. Also, when I had the SR500, it was great fun to keep up with faster bikes because you had to work so hard to stay with them. Conversely, the 1290 Super Duke R EVO is amazing fun, you can spank it hard in places that the 890 falls flat on, but you also can just putt along and enjoy the scenery on both. I went pretty well on my KTM 525 SMR and did some amazing stuff, sliding front and rear, lifting the rear into corners, learned a lot on that bike. Of course, I went faster on my RC8R and my Gixxer 750. So I would say, "Both".
Little bikes are fun, to a point. I enjoy my LC8 motors much more than in line 4's. I have been a junkie for sporting V-twins since my Suzuki TL1000R/S days. Nothing pulls like that Super Duke and my almost favorite bike of all time is my 990 Super Duke.
So, that is my best non-answer. But, slow bike fast and fast bike fast are both great.