Which Barbarian build should I use to level and farm in Season 14?

Whirlwind is still the sensible pick for most seasonal Barbarians. You can start with it before your gear is sorted, and it keeps working as the character moves into Torment. The appeal is simple: you damage enemies while moving, rather than stopping to set up every attack. That makes Helltides, dungeons, Whispers, and general map travel feel much less tiring. Fury can be awkward at first, so do not spin through empty space just because the skill is ready. Pull a decent pack together, use Whirlwind for a short burst, then move on. Rallying Cry helps with movement and resource flow, while War Cry and Challenging Shout give you useful damage and defence windows. Leap is handy for getting into a pack or escaping a bad position. You will soon notice that cooldown reduction matters nearly as much as raw damage. More Shout and Wrath of the Berserker uptime means better damage, tougher fights, and fewer dead moments. Gohr's Devastating Grips are a major target, but the build can function before they drop. Tibault's Will, Ramaladni's Magnum Opus, and Rage of Harrogath can also smooth out Fury and cooldown problems. If your resource pool is struggling, look for Fury generation, regeneration, cost reduction, and Fury on kill before chasing another small damage increase. Spending a little time improving your route and keeping your Fury above empty will help more than blindly raising the difficulty. A few well-chosen upgrades, or some D4 Gold for sensible early purchases, can make that transition less frustrating.

Is Flame Charge better than Whirlwind for high-end Barbarian pushing?

For serious Pit or Tower pushing, Flame Charge has the higher ceiling. It is not simply Whirlwind with a different button, though. The build revolves around Charge, Burning damage, and Ground Stomp, with Chainscourged Mail acting as the key piece. Without that Unique, the setup loses the interaction that makes it worthwhile. Once the gear is in place, the usual sequence is to maintain your Shouts, use Charge to engage, cast Ground Stomp, and Charge again when the item effect allows it. The timing takes practice. Press things in the wrong order and the damage falls off quickly. That is why Flame Charge can feel weak when copied too early, even if a geared player is clearing far beyond your current level. It also asks more from your positioning and Fury management. Ramaladni's Magnum Opus remains useful, while Tuskhelm of Joritz the Mighty, cooldown reduction, Strength, and damage-over-time scaling all need to work together. Do not break a functional Whirlwind character just because a guide calls Flame Charge the strongest push build. Farm with Whirlwind, collect Burning-related gear, build your Glyphs, and make the switch when Chainscourged Mail and the supporting pieces are ready. Whirlwind is the better journey for most players; Flame Charge is the specialist option once your gear and patience can support it. If you're filling the last gaps in that transition, cheap Diablo IV Gold can help with practical upgrades while you keep farming for the items that actually define the build.