I know Deadeye/Raider is popular, but if you have played Raider/Pathfinder enough in past few leagues. Prefer a tankier (marauder?) build, possibly looking to try an Ascendant (never tried one) Suggestion as to why one is better: Champion and Scion - Slayer / Champion + ? or Suggestions? Jugg?
I think that you get the most value, pound for pound, out of champion. Tanky with more multipliers. It is the easiest to gear and the ascendancy will carry you through the most part of the game. It is better for a "starter" build, imo. If you want to make your gear better, you should to spend some PoE Currency cheap on it.
Other people would argue that scion - raider/slayer is better, and they may be right. Overleech is a hell of a defensive mechanic and is super good for end game bosses and the damage output after frenzies is better. Its not "tanky", per se, but is not easy to kill with a good enough life pool.
Another good choice would be Inquisitor. Ele penetration is nutty as long as you crit, which shouldn't be too hard since you have access to plenty crit nodes from tree+ascendancy. If you decide to go scion or champion I would like to see a pob of the skill tree you are going to use.
Highest damage molten strike I've seen and been able to achieve was ele inquis with claws. Ends up actually being pretty tanky due to reduced ele damage taken along with 6k+ hp and some dodge. Shouldn't really ever get 1 shot unless you stand in a slam and all of the balls act like old vaal pact. It must be a pleasant journey. Just gather cheap PoE Items for trade on U4GM to start your wonderful experience.