Well, if you have a Mesa Boogie Scout, you are pretty well set. However, one of the EA combos would be even more flexible. Of course, if you are talking separate amp & speaker combination, then you have a lot more options. Personally, on the head side, I like the iAMPs, the Thunderfunk, and the Walkabout. For cabs, I find EA and Accugroove to be the most flexible, as they are very uncolored and accurate, hence allowing you greater freedom to tweak to your tonal desire (even though I like them prett un-eq'd, myself). Epifani and Bergantino cabs are only slightly more colored, and will also allow a good deal of flexibility. While I have not tried them myself, ACME and Schroeder cabs also get high marks in the flexibility department.
Good luck, Tom.