BP Core AI
Improved Spellhold
Improved Suldanessallar
Wand of Orcus
-----(all BP originals)-----
Small Teeth Pass by Kensai Ryu (KR)
Improved Kangaxx - KR
Improved Crypt King--KR
Gnome Fighter/Illusionist--KR
Improved Encounters (combo of City & Wilderness) -- KR and GB
Lich in the Docks -- Gebhard Blucher (GB)
Red Badge -- Westley Weimer (WW)
Kuroisan -- WW
The Ritual -- WW(?)
Level-50 ruleset -- void if TDD is installed
Ascension -- David Gaider and IEEAIS
Note that each of these components differs slightly from the original. All those non-weimer Tactics components were taken from original sources, not Tactics. I have author's permission to do what I please, and I have exercised it. Mostly bugfixes, but some actual improvements.
Still hardwired into BP (and there to stay):
Improved Mind Flayers -- GB
Improved Dragons -- KR
Improved Copper Coronet -- KR (goes nice with BP's Improved Slavers compound

Improved Horns of Valhalla -- Cirerrek
Improved Tanner's -- Jacky-O (only appears in BP)
Improved Nymphs -- BP original--I never looked at Tactics version, so hard to say what differs
Improved Golems -- WW
Improved Undead -- WW (I didn't start with his work as a base, but he did it first)
Improved Drow -- KR (I believe D0Tweaks offers this component these days, so don't double up)
Horred's Lair (another BP original)
Improved Bodhi/Vampire Lair -- My own, nothing to do with Tactics
Improved Ilyich -- another BP original, entirely different from Tactics (not anywhere near as overpowered IMO, but much cooler

Improved Beholders Lair -- My own AI for them (not Xyx'). Many recent improvements. Woe if you try this on INSANE with high-lvl party! *I'm also considering fusing SimDing0's eyestalk scripts with my own.*

(Slightly) Improved Sahuagin City -- a recent addition, not as tough as Tactics version
And probably several other things I cannot recall at the time. I have plans to improve Irenicus final battle as well, but haven't started yet. If I find the time, I'll add it before public release. If not....before the final version.
This does not include the dozens of improved creatures that BP itself has to offer (Demons, Beholders, Spiders, Vampires and "Shadows"--wraiths, mists, etc-- (all very different from Tactics!) and Hell Hounds --just to name a few I can think of offhand). Nor individual creature improvements. Nor AI improvements. Nor individual area enhancements (usually more monsters, depending on level/XP, number in party, and difficulty slider).
Note on AI/Creature improvements: It has always been BP's mission to offer more challenging, more intelligent, more realistic, more diverse opponents while resorting to as little cheese as is possible. I won't say there is "no cheese tactics" in BP, but as little as I could get away with and still keep things interesting.
As far as Enhanced Creatures goes, I have been in touch with the author, and made several important recommendations. I hope he truly considers them; without, there will be little-to-no chance of compatability.
I'd like to see it, too.
As far as any remaining Tactic components go--well, they will have to be looked at individually. Tactics is still an "old-style" weidu mod. Meaning: it doesn't do all of the fancy hex-patching we've come to expect (whether we are aware of it or not). It tends to overwrite existing game resources, which makes life hell on other people's mods. This was the original reason I petitioned Weimer and the other authors to "hardwire" their work into BP. That also includes BP's version of Ascension. Hopefully somebody (if not Weimer) brings this community classic up to date.