This sounds fascinating. Could you please give us some more in depth info on this, maybe level by level progression and thinking behind the build, tactics etc... ?
Sure. I was thinking about how Advantage works out to be about equivalent to a +5 (but also doubles crit chance) and since that +5 is more than the +2 you would get going from 16 to 20 in a main Stat or even the +3 between 14 and 20. So ultimately I was thinking about the value of re-rolls or extra rolls versus static modifiers.
There are a lot of ways to get some extra rolls in this game, but I wanted to focus on how best to use them on a character I would like. Somebody who is good with a Longsword or Greatsword but also decent a Longbow.
I get three sources of re-rolls with this guy, Reckless attack, Lucky, and Stalker's flurry.
Starting V Human with Lucky. Point buy and Human bonuses get me 14, 14, 14, 11, 14, 8.
At first I took Ranger Gloomstalker to 5 for Extra Attack grabbing Mobile at 4, then 2 in Barb for Reckless Attack. So already he's got advantage on all melee attacks, and Gloomstalker gives you one extra attack in the first round of each combat

. If he does miss he has Lucky to give him another chance at hitting (and critting).
But enemies having advantage against you is bad, so you want to mitigate that. I decide that using Mobile I could use the extra movement from Mobile, Gloomstalker, and potentially Longstrider (hopefully caster before combat begins) to get into combat, Recklessly smack people with my Greatsword, then move out of their range with mobile. They can't attack me with AoOs and if I can move far enough not attack me at all. Completely mitigating the negative of Reckless Attack thus saving me a use of my limited Rages.
At this point I could have stayed with Ranger to 11 for Stalker's Flurry which could turn one miss per turn into another re-roll, but I decided to start getting more out of that Greatsword, so 4 levels in Fighter got me Action Surge, Expanded Crit chance (Champion) and a Feat (GWM)
And that's pretty much it so far. Assuming the campaign goes far enough 6 more levels in Ranger will get me Stalkers Flurry. One more in Barb will get me Bear Totem or Zealot, I haven't decided yet. Probably going to grab Observant to round out that odd Int score and up Perception.
It's not optimized by any means. There's no doubt it would work better with 20 Strength, but I don't find it "necessary" for the character. It's playable and fun.
Also it's fairly decent at Range too. +2 from Dex and Proficiency is not that bad, and Lucky and Stalker's Flurry both will help out with misses. Alternatively I could have gone Samurai of Champion for Advantage that will work at Range instead of expanded crit range, but I just love combining Reckless Attack with 19-20 Crits.
Oh and one more note. This was using PHB Ranger. It would be much better if I were using Revised Ranger. Advantage on the first round of combat would save me from using Reckless Attack on those Rounds. And Revised Rangers getting Bonus Action Dash works even better with Mobile. I like what I have, but I can't wait to see what alternate Ranger Rules come out of the whole Revised discussion.