Hey I'm down to 1600+ with my zHP icicle miner (best option IMO). Check out poe.ninja for the builds they use down there. You pretty much have to mirror their builds (it's expensive FYI - deep delving aint cheap).
You could go icicle mines, brands, or ice shot right now - those are the big three. Icicle mines are the most reliable and best starter build, brands are top DPS but insanely expensive to gear, and ice shot mines requires a niche gameplay style (no 360 attacks like icicle mine) so you have to get used to that.
Not many people have enough skill to deep delve so you won't see as many guides on it. This guy is the top icicle miner right now and he made a pretty good guide:
https://www.pathofexile.com/forum/view-thread/2903986