Just making sure. So tell us about the Champion Fighter and Barbarian in one of those single encounter days. How were they built? What actions did they take? How often was the Barbarian reckless attacking? How many rounds did the encounter go? Did they get any assistance from the other party members?
I'm not digging through the last 6 years of 5e fights I've run for you, but if you want to do so there are a ton of text chat game logs at
Forgotten Realms Campaigns &
Varisia: Rise of the Runelords & NSFW
Sensitive Content Warning - the latter has the early years games 2015-16 before I went over to 1 week long rests.
My impressions: Typically Champions are played by the less minmaxy players to start with, while most Barbarians are Bear Totem for maximum survivability. The Champions don't always Action Surge straight off. The Bear-Barians tend not to Reckless much, preferring to keep a good AC and wear down the enemy over a large number of combat rounds (say 6-8 like I said), by which time the Champions are usually badly bashed up. There's usually some support from other squishy PCs eg in Wilderlands the early group was typically Berserker Barbarian, Champion Fighter, Assassin Rogue and a Warlock of the Fey. The Rogue & Barbarian players were quite skilled, the other two not.
In my current Faerun games one group has a Goliath Champion Fighter and a Berserker Barbarian. The Barbarian is higher level, the Fighter player having lost two other PCs so far, so cannot compare directly esp as it's currently Barb-5 vs Fighter-4 so the Barb has x2 offence right off. Having lots of encounters between LRs definitely helps though.
Edit: My current Faerun Adventures PC groups are:
(1)
Greeba of Soravia (Jelena) Half-Orc female Barbarian-5 (Berserker) XP 10,375/14,000
AC 18 (scale, shield, DEX+2)
HP 50 (14+9/level),
+1 warhammer; flametongue longsword P-PER 10 P-INV 9 P-INS 13
Gorlock the Warlock (Tony) Half-Elf male Celestial Warlock-5 XP 10,375/14,000
AC 15 HP 43 (11+8/level) P-PER 11 P-INV 11 P-INS 11.
Wisteria of Skullspire (Jelly) Moon Elf female Grave Cleric-5 XP 9,791/14,000
AC 17 HP 38 (10+7/lvl)
P-PER 16 P-INV 12
P-INS 16. MI:
+1 longbow
Eamon of the Yellow Rose (Bill) Human male Monk-5 (Kensai) XP 9,321/14,000
AC 16/18 HP 33 (9+6/lvl) P-PER 12 P-INV 10 P-INS 15 MI:
+1 longsword
Nathia Truefist (Kim) Goliath female Fighter-4 (Champion) XP 5,549/6,500
AC 16/18 HP 36 (12+8/lvl) P-PER 12 P-INV 9 P-INS 10
Joell Elderberry (Max) Aasimar male Paladin-4 (Oath of Conquest) XP 3,149/6500
AC 21 (plate & shield)
HP 32 (11+7/lvl) P-PER 11 P-INV 9 P-INS 11
Blurb (Phil) Firbolg male Forest Druid-3 XP 900/2700
AC 16 HP 24 P-PER 13 P-INV 9 P-INS 13
Mac (Matt) Hill Dwarf male Hunter Ranger-3 XP 1,922/2,700 AC 17 HP 34 (14+10/lvl) P-PER 14 P-INV 9 P-INS 12
Quasi-PC
Trystan, the Bard of Leth (Jelly) Half-Elf male Bard-4 XP 2,700/2,700
AC 15 HP 31 P-PER 10 P-INV 11 P-INS 10
(2)
Norrin Son of Thorin (Geoff) Human male Fighter-6 (Champion) PB+3 XP 19,936/23,000
AC 22 (plate +1 & shield +1)
HP 58 (13+9/level)
P-PER 15 P-INV 12
P-INS 15 MI:
+1 Nar 'hero sword' longsword, +1 plate armour, +1 shield, +1 Duergar greatsword
Strohm of Leth (Muiz) Sun Elf male Fighter-6 (Eldritch Knight) XP 18,167/23,000
AC 19 (orog plate, defence style)
HP 52 (12+8/lvl) P-PER 12 P-INV 12 P-INS 9. MI:
+2 Greatsword - Excruciator, the Sword of Amaul, aka the Sword of the Sorcerer (sheds light as per spell on command)
Malied Edicast (James) Half-Elf male Wizard-6 XP 17,318/23,000
AC 13/16 mage armour
HP 26 (6+4/lvl) P-PER 14
P-INV 18 P-INS 11. Blessing: +2 INT from Gina the Gynosphinx
Fraener ap Durgeddin (Chris) Mountain Dwarf male Forge Cleric-5 XP 13,927/14,000
AC 22 (AC19 plate armour +1, +3 for shield blessed to +1)
HP 48 (12+9/lvl) E: Durgeddin's own
+1 full plate armour (+0/
+1 at 5th level), +1 Duergar warhammer,
+2 Mace. P-PER 12 P-INV 10
P-INS 15
Ted (Matt) Half-Orc male Rogue-5 (Thief) XP 7,465/14,000 AC 15 (studded) HP 38 (10+7/lvl) P-PER 15 P-INV 9 P-INS 11 MI: Ostrikka's/Jack's gauntlets of ogre power STR 19, +1 Durgeddin Rapier from Tenho, Barbara's Rope of Climbing
Queale (Keelia) Half-Elf female Horizon Walker Ranger-4 XP 7,096/6,500>14,000 AC 16 HP 40 (13+9/level) P-PER 15 P-INV 12 P-INS 15 MI: cute rabbit fur slippers of elvenkind
Shivers (Rich), Human male Rogue-3>4 (Assassin) XP 3,999/2,700>6,500
AC 14 HP 21>29 (9+6/lvl, rolled 8 hp for 4th) P-PER 13 P-INV 13 P-INS 11
With an open sandbox style, 1 hour SR and 1 hour LR, no Feats or Multiclassing, the classes seem pretty balanced to me. Without Feats, Humans are definitely weak - esp as there's a lot of dungeoncrawling where darkvision helps.