Glad the topic ignited some conversation! So much to talk about!
In 2000-2500 pt games, I always run them in horde, with a min. of 30 units. Uusually with a TP or TK. I like bringing a Necrotect or Ramhotep personally as they're not very expensive and could make a huge difference with hatred/frenzy.
Personally, I run them with halberds (mostly for WYSIWYG reasons) but I also don't use them as an anvil, and prefer any extra killing they can do. I'd rather use a big block of skeletons as the anvil, if I can. But again, I try to follow WYSIWYG to the best of my abilities.
In 9th Age, which I played a bit, I also used a BSB, and in 8th I've brought him once or twice with no too incredible results.
Basically, because when I play here at home, we use a small table and 1250~ points, I don't bring a full 35+ horde of TKs. What I found doing this is that a regular unit of 20 underperforms for their cost. I know some of you mentioned "well they can get massive buffs!", which is true. But, again, at 1250 pt, I've usually brought a lvl 2, which makes the spell selections a bit more random. In the two games we played over the last 2 weekends, I rolled Cursed Blades (KB on a 5 for them) both times.