It is not clear what a ranger does to me too. They are wilderness warriors. Ok, that is just some skills that make them effective in a particular terrain. That sounds like you can give them expertise in a few nature skills. It is also just skills so could encompass a background. I understand Mearls dilemma. The other ranger things are a bit of a grab bag. Should they be nature spellcasters too? They are in the nature. Sure why not? Should they be roguish outdoor scouts. Yeah sure, stealth and sneaky. The big key for me is they are a skill based class, knowing stuff. Monster knowledge. Knowing the weaknesses of monsters. Researcher. Van Helsing. A lone wolf, much like a rogue.
All good points.
I still believe that the best approach is to base the Ranger roughly off Aragorn, plus some additional baggage that came across D&D editions, and this is exactly what they have done in 5e. Combat based on direct experience, wilderness knowledge, tracking, outdoor/travel skills, nature-ish spells, they are all traits of the Ranger and I don't think it's a good idea to remove them. Other stuff like fighting styles (as in 3.5 two-weapon-fighting vs archery) is redundant and does not need to stay. Animal companion, as you say, should also not be a default... sure one of the most famous D&D Ranger had an animal companion, but pets are (1) always tricky to implement (and in fact it's the one thing about Rangers/Beastmaster that gets criticized in forums), (2) seriously disliked by a significant amount of players and DMs, and (3) plenty of famous non-Ranger literary characters also had a pet. In short, animal companion is the
worst possible idea to base the Ranger around!
I don't think that "scout" is a concept strong enough to replace the Ranger as a class. It's a warrior with wilderness skills, or a nature-oriented rogue, or a Ranger without spells... or even less than these, and in fact it's something that 5e designers turned into a
background.
So my bottom line is, either leave the
Ranger be what it already is, or remove it from D&D entirely, but no need for a 'rebuild' or replacement.
I think the animal companion thing should be backed out of as a thing. I think anyone should be able to have an animal companion, or familiar, or henchman, or special mount. If you want to dedicate your resources to it (spells and feats) then by all means have one. A whole class dedicated to it though seems odd.