I like resource pools. Based on comments on this thread, I can see that it is because I look at the game more "boardgame" than "RPG"... the roleplaying exists to get me from fight A to fight B... I want a reason for the fight (i.e. I'm not looking for "Skirmish Mode" in CRPG), but the fight is the key for me and about half my players. So I'm all in on managing (or, as DM, depleting) resources. And 5e took away the mundane resources (torches?
Light. Food?
Goodberry. Tools?
Mending and
Fabricate and class abilities and tool proficiencies to make more), leaving me (DM) with fewer options.
I like the idea of a Stamina pool for martials to use to empower their abilities, and a Mana pool for the casters to empower their spells. (Like
@RenleyRenfield said, wrt Mana, on page 1.) Multiclass caster/martial? Stamina and Mana... but less of both.
I like the Escalation Die as an influence in the pool... the size of the Die impacts the effectiveness of the Power/Action, to powerful actions are "better" later in the fight for the same resource cost... but there's the Sid Meier "interesting decision loop" of whether its better to spend the resource early, and maybe win (or ease) sooner? I'm playing a phone game right now called Mecharashi, where my missile mech can launch either a 3pt 3x3 rocket strike, or a 6pt 5x5 spread rocket strike that hits everything for 150% damage. On round 1, it only has 5 pts to spend, so obviously the only choice is the 3pt spread... but if I hit 3+ targets, I get a point back. So now I'm sitting there with 3pts again... I can spend them on a second strike
now (maybe even against the same foes, further weakening them), or save it for enext round, when I'll now have
6 pts available to launch the 5x5 strike! And even then, depending on multiple factors (like scoring kills), I might be able to launch a 6pt strike
and a 3pt strike... or save up for another 6pt? That's an interesting decision (for me) - killing some foes now by spending resources
now that are "less efficient"? or waiting for better timing/position/power?
I like Short Rest recharge for most things - at risk of getting blacklisted, I
liked "Encounter powers" from 4e, in this concept, if you consider them "boosted abilities because I spent a Short Rest resource" - because it encourages players to
use their abilities. And I like it combined with Long Rest recharge (i.e. "dailies") so there's still a little something special for when you need it. Dying (or resting!) with dailies unspent happens... saving... waiting... whoops! Shoulda spent! Doing the same with Short Rest abilities unspent? feels stupid.
So I'd be all about a Stamina / Mana resource that enhances abilities/spells, and recharges with a short rest, but might be influenced by Escalation,
paired with one or more Daily abilities/resources that are usable only "at the utmost end of need" (- Denethor) and might not even recharge with
one night's sleep!
And to keep RP-focus happy, some of the options available should be noncombat AND NOT BE AT THE COST OF NOT TAKING A COMBAT OPTION!!!, and would recharge at the end of a "Scene". The Fighter, for example -perhaps by virtue of Background, Skill, or well-written backstory- spends some Stamina to be an excellent partner in the evening's courtly dances, despite being an absolute boor when he opens his mouth (low CHA/Persuade). The wizard could spend some Mana to enhance his
dancing lights cantrip to be more "fireworks" and "entertaining wisps" to (pardon the pun) enchant the crowd, without the DM needing to go "um, acksually, only 4 wisps, in 10' square, and music disrupts your Concentration"....