As its been said, unless you have a strong weapon, marks is not the way to start out. you'd want at least a 359 pvp weapon from justice points at this stage in the game before you switch. In my opinion, both survival and beast mastery are viable. I would lean towards survival because you get more control and your attacks ignore armor since their mostly elemental and mastery makes them stronger. This is big when your physical attacks are nothing. BM's also good because you get some added survivability with your bond talent and your pet becomes a more significant part of your damage which is good since pet damage doesn't have to scale with weapon damage. Your pets attacks are still physical though, so you'll still be at a disadvantage against armor with your low stats.
What I would recommend is go for a survival build and play glass cannon (wear your highest stat gear regardless of pvp or pve) to try and increase your damage against high resil targets. You have to play dfensively so you don't get creamed, but this will help you overcome high resil players while you yourself are getting your resil gear. Now since you're fresh 85 and pvp honor is 371, you'll probably just be replacing your gear as you get enough honor to do so, but I would replace lowest item levels first and keep your stronger pve pieces (maybe even boe epics) as long as you can.
Another option, if you're a crafter, or if you have the gold/farming time is to craft the 358 pvp gear. I'm cheap and have limited time, so I did the other method on my rogue. Last thing I replaced was my 353 boe gloves and first thing was my low 300 ilvl armor. it's up to you. I realize I diverted some with gearing, but as I said I would recommend survival to start as you gear up then go marks when you have a decent weapon. All 3 are viable so even after you're geared, play what you prefer.