Damn it, I leave for a while and miss a great thread.
Anyway, might be a bit late but here's my input:
1. Don't underestimate a good sidearm, especially if you're using a pike. Don't listen to the BS about sidearms not being useful. There are situations where a pike/longspear is simply not a good option, and having a good sidearm can really save your ass. If you get the hang of switching between your pike and sidearm at the right times, it can net you some easy, free hits as well. My sidearm of choice is the langes messer in 2H mode.
2. Balanced builds, especially with a slight focus on strength are, imo, the way to go. Personally I use 21/18 with 7 IF, 7 PS, 6 Ath, and 3 WM (99 2H prof, 98 polearm prof). If you go low strength, there's just too high a chance of glancing.
3. This is mostly to non-pikemen but: DON'T CONFUSE THE PIKE AND LONGSPEAR! They are 2 very different, distinct weapons. The longspear is a much better balanced weapon, and has a lot fewer weaknesses, but the 55 range reduction can really be a pain, especially when fighting Pikes.