I might recommend
Zhayolm over Bhaflau. A few notes:
+ Pros: Faster runs, easier boss for THF (no special DT mechanics), minimal fighting for unlocks.
- Cons: About 13 less alexandrite per run (unless you're very patient/daring/lucky), ilevel gear not available until floor 5.
I recommend going /RDM here for Phalanx, Blink, Haste, and Cures. Having the magic accuracy from ilevel weapons also makes debuffs like sleep land if you really need it. General path for quick alex farming would look like this:
Floor 1: Take advantage of /RDM buffs to make this safer. Try to pull enemies one at a time, as well. Only really need to unlock back/waist, rings/earrings, and HP. Get some TP on a weak dude after you've unlocked stuff.
Floor 2: Go up.
Floor 3: Go up. Direction doesn't really matter.
Floor 4: Go up. You could farm alex here, but it's very dangerous without any armor.
Floor 5: Buff up and pull a single Gear. Use Bully + SA WS to one shot it, which will unlock the rest of your armor. Even if you get links, the single strong WS should definitely kill the Gear, and from then on it's pretty simple. Now you're ready to go up, but you can kill a few more gears or chariots if you really care.
Floor 6: Kill everything in the big room except the lone Rampart in the back (no time limit). This is the spawn condition for the Hydra from the Rampart. Hydra's even easier than Khimaira and has no DT stuff unless it does physical shield.
Floor 7: Alfard is easier than Khrysokhimaira since you don't have to worry about Fulmination.