Definitives, Commemoratives Or Mixed ?

when buying kiloware, do you prefer definitives, commemoratives or mixed ? What are your "pro's" and "con's" for each ?

I don't buy or collect kiloware, but if I had my choice I'd prefer definitives, especially if some mid-to-higher range denominations show up and not just the current regular postal rate stamps.

I've purchased just a very few used collections over the course of time, mainly Scandinavia, and only the definitives jump out as interesting to me. There are some sets that kind of bridge the commemorative-definitive paradigm and I always struggle to decide which to include in my collection. The sets I speak of are clearly commemorating something, always with dates and/or names of those being commemorated, BUT, they also cover a very broad range of current postal rates.

Sorry to get off topic, but my vote is definitives as long as the kiloware does not have 10-infinity of each definitive stamp in the lot.