Here are a few questions for everyone.
1) If the ranger simply received Expertise instead of Favored Enemy and Natural Explorer, would it still feel like a ranger?
It certainly
could. It would depend on the implementation. There is also the fact that the ranger, like the Fighter and the Thief, need to have 2 starting/level 1 features. Now, knowing your preference, I guess that would be Expertise and Spellcasting. FOr the non-spell-based ranger fans, it would need to be Expertise and something else.
If you are asking if "Expertise" could replace both Natural Explorer and Favored Enemy...I would say, then, say no. But "Expertise" in wilderness situations, perhaps called Wilderness Expertise (as in my own ranger write-up, if you'd give that a look
) is most certainly a reasonable feature for the class to have...imo.
My current iteration of the Wilderness Expertise feature for my ranger rewrite grants the ranger their Proficiency bonus added to Nature, Survival and Stealth rolls...in any terrain. In their chosen terrain, the prof. bonus is doubled. So, useful all of the time. Better/superstar in their chosen terrain. That work for everyone? No one's arguing against that kind of thing, it seems.
2) Would a favored organization variant (choose mage or thieves guilds, city guards, druid circle, or any other organization as a target) for favored enemy match ranger flavor?
I suppose. Though I recall some unwritten/unspoken rule about choosing things like "humans, elves, etc..., [PC races]" as favored enemies. Not explicitly "not allowed", but in "bad taste/poor game sportsmanship". Naturally, that was several editions ago and modern editions don't give concern to such things.
I don't think you could make "an organization" their favored enemy. How do they fight "Mages" or "Thieves", "Clerics of Ool", "the Dark Paladins of Badguy", etc... I could see the classes becoming fair game. So, if you can fight thieves well...whether they're in a guild, or even specific singular guild, or not shouldn't really matter.
But, does it fit the flavor? Yeah, sure. I suppose.
3) Should favored enemy be a choice (meaning a ranger chooses 2 of favored enemies, terrains, and organizations)
See no reason why it couldn't be. So you could have 1 favored enemy and 1 favored terrain...or 2 favored organizations or 1 terrain and 1 organization, etc etc..., you mean? Yeah. Could be.
Should be?...not sure about that.
4) Could you see rangers using nontraditional fighting style based on the ranger's preferred terrain (heavy armored arctic rangers, unarmored coastal rangers, grassland ranged with shields)?
Based on the terrain? I would rather not go here. This kind of thing is better left to player wishes and common sense.
I am really not interested in getting into arguments over the coastal ranger player's assertion that they are able to swim in their armor...or that they're AC is not diminished being unarmored in the water...or why/how heavy armor has to do with arctic conditions/keeps them warmer...whatever/however that would go.
Just seems like...on its face, a cool/flavorful idea that...in practice would end up opening more unnecessary cans of worms than its worth. In other words, the opportunities/chances for abuse/argument/problems...overall "detracting from the game" will/would eventually outweigh whatever the feature is aimed to add.
But I could be wrong.