1. Have approx 700k+ Gold on a character you are leveling.
2. At the start of each Baal run, run and check Larzuk and Anya.
3. Try not to die and lose all that sweet gold.
4. Level and hopefully profit.
As long as your at 75+ your chances of getting good rolls are essentially the same either way--the only real factors then are the difficulty level and your character level. Anya's biggest advantage is that she's really quick to run if you have the Red Portal open. She also sells more claws per screen on average, and even though only one of the two types she sells is outstanding for a trapper everything else makes her more efficient by far.
Asheara might be my second choice (or maybe NM Anya) but there's really no reason to run her if you've got Anya and the Portal available.