I've been analyzing the B/X wilderness encounter tables lately, and while I'll probably stick to that for now, I think since this blog talks about Basic, AD&D and (sometimes) 5e, one small observation is in order:
As often happens, the encounter tables in in B/X are oversimplified and the ones in AD&D are overcomplicated.
And 5e got us beat again - but it took them a while!
Let me explain.
The B/X wilderness encounter tables fit a couple of pages. While I love the fact that they are so slim, they produce strange results: dragons do not follow their natural habitats, there are too many dragon and basilisks, every result requires a sub-table, etc.
There are (about) 96 possible results for each terrain, but many are repeated; dragons about happen 6% to 12% of the time.
AD&D, on the other hand, contains about a dozen pages of tables and sub-tables, using d100.
You'd think they'd take the opportunity to organize all entries in single d100 table, but no, we have tables and sub-tables with incredible levels of detail; some monster will appear only 0.1% of the time.
It also has famous a sub-table to describe which type of prostitute appears if you ever find one...
[I'll ignore 2e, 3e and 4e for now because I haven't played them as much. From a brief glance, 2e hasn't included such tables in the three core rulebooks, and 3e is even worse than 5e in forcing that encounters are adapted to the PC's needs. I'm guessing 4e is the same.].
5e did not even HAVE many random encounter tables at first - each table was part of a setting, which is fair enough if you're using a published setting - it only suggested you created your own and provided a small example, with about 20 entries and using 1d12+1d8 for some reason.
The tables included in the settings are often very good, but that's not what I am looking for. [BTW, this is why I haven't been analyzing random encounters in dungeons - I think these MUST be connected to each particular dungeon, and I simply cannot stomach a hill giant randomly appearing in a deep dungeon fro no reason].
Fortunately, Xanathar's Guide to Everything partially fixed that.
It contains simple d100 tables (simpler than AD&D but more complete than B/X) that list not only monsters but also number appearing - plus a few "cosmetic" encounters that don't really belong here (rain, "the sounds of drums", etc.).
Unfortunately, these tables are separated by CR, and are too slim unless combined.
This is a bad thing on principle - the world shouldn't conform to PC's level - and, combined with the existing tables, it is even worse - that means that past level 11 there is no more "rain" encounter but now there are "drums" for some reason (looking at the table above, I assume the yuan-ti like to play drums, but only when the PC's reach level 11).
Fortunately, you can integrate all these tables by adding another roll [e.g., "roll an extra d10, with 1-4: tier 1, 5-7: tier 2, 8-9: tier 3, 0: tier 4" - thank you Evan for commenting here!]
Maybe there is a game out there that uses the best of AD&D, BX and 5e. The tables in BFRPG look decent, but a bit slim. Dragons and rarer and appear in appropriate biomes! Yay!
I guess I could adapt my favorite bits from all these sources, but it is unlikely that no one else has compiled a better table... let me know in the comments!