Try and get your hands on each to see how they feel and fit you.
If the gun doesn't feel right, then it won't matter which you choose as you won't be able to shoot it competitively.
Barrel length, overall weight, stock dimensions, all play a factor in how you are able to handle the gun and swing it around as you engage targets.
Next you need to make an educated guess on how serious you are going to get regarding competition and total round count you are going to put through the gun.
In terms of quality of materials and longevity of parts, you get what you pay for.
Both guns are gas operated and both will need regular maintenance to ensure you don't have a stoppage during a match.
As far as shooting left, the Vmax safety can be reversed so that shouldn't be an issue for you.
The top mount safety is a nice feature, but depending on the matches you will be going to and their abandonment rules, the top safety is in an exposed position and can accidentally be moved while transitioning to your next gun.
Jerry M was DQ'd from a match because his safety reengaged while dumping the shotgun into a barrel.
Both need a bit of work to be in ideal shape for serious competition.
Loading ports opened up, lifters extended, fore ends modified so they are out of the way etc.
Between the two, I would pick the versamax.
I haven't had a chance to put rounds through it yet, but I built up a Stoeger for 3gun and just need time/weather cooperation to run it through its paces.
May be another cost effective alternative for some.
I went through all of this about 4-5 years ago.
Fortunately I was in a position to play with all of the platforms and decide which worked best for me.
I settled on the Benelli M2 because it had the right overall weight/balance I wanted, and it had the proven track record in the US.
Regardless of which platform you end up with, it will cost you over $1000 by the time its all said and done.
Try and handle each gun in your price rage/on your wish list and make an informed decision.
It would suck to buy a gun just to find out you don't like something about it and either have to live with it or end up having to sell it and lose money on the deal.