Hmm kinda hard because some of my currently favorite DC figures happen to be modded or outright customs I made for myself, haha!
Well I tried my best but in terms of untouched/non-modded favorite vanilla figures, here it goes:
1) DCC Talon (Greg Capullo Designer Series)
2) DCUC Deathstroke
3) Mafex Batman 2.0 (TDKR)
4) DCC Batman and Phantasm 2-pack (BTAS)
5) Total Heroes Black Manta
DCC has really been going strong but I can't help but feel that the hype all started during the time when the Greg Capullo designer series hit, and their rendition of the William Cobb Talon just turned out so great especially with it being the first figure of a new character. While Mattel hasn't been as strong recently, DCUC was still great for its time and we got standout figures like the DCUC Deathstroke that has basically remained as the definitive figure for his classic design (until maybe DCC puts out their Icons version?). Mafex Batman 2.0 is probably the best available Baleman right now though I'm curious to see how the upcoming Figuarts will turn out. Number 4 is kind of a cheat but honestly it's such a great pack and basically gives you a proper BTAS Batman along with Phantasm. From the kid-friendly Total Heroes line by Mattel, there's the deluxe set Black Manta which doubles as a Young Justice and New 52 amalgam of the character.
Admittedly if I were to finish my Black Manta custom, I can easily see it ranking top 1 (lol). That said, I'm definitely looking forward to a lot of DCC's upcoming figures, especially the TV shows, Icons and movie stuff.