Either should do well. I shoot VLDs out of my 270 and AB out my 300. Both will do the job with a good shot. The problem isn't that elk are bulletproof, its where they tend to go when you don't knock them down that causes problems. Like any wounded animal they will find they thickest nastiest terrain to bed down when hit. In elk country that can cause a lot more work when getting them out.
My personal experience is with ABs in 30cal on many species. My experience is that they are predictable. I'm not sure where the comments about lack of penetration come from, if whatever cartridge you are shooting at a given range can't get adequate penetration with a mushrooming bullet, I'd question the choice of cartridge and not bullet. I've seen multiple cases of pass thrus on elk 500-800 yards. Someone stupidly took a rear end shot with my rifle on a whitetail at 400 yards and the bullet nearly came out the front, with everything in between destroyed.
It is my second hand observations of VLD performance which has prevented me from having first hand experience. With Bergers shot by hunting buddies, I've observed inconsistent and sometimes explosive performance even at extended ranges where the velocity effects should be mitigated. This was on antelope, deer, and mule deer, so I would expect the results on elk to be even worse.
Just my opinion, but based on what I've seen I'll stick with ABs.
Killed a 374" bull with a 300 wsm with 168bergers from HSM last fall.300 yards took a step left and put another in him and he just tipped over.He was dead on the first one but still standing so I got another in him.It was late afternoon so we didn't open him up.
I killed elk this month with accubond, eldx and SST all 160 class from 7 mm rem mag all died fast I will try to post pics of bullets I guess the site won't take my pics but I got back 130 grs of a 160 accubond and around 1w0 of eldx and about 50 gr of SST all lung shot at one time and place no shots under 450 yds so I am now an accubond buyer