Here are my first 31 thoughts about what I want from/in a rpg combat-- from a player's perspective. I'll probably have more later, but I wanted symmetry with Baskin Robins (they have 31 flavors, right...?). Some of this is mechanics, and some GM based.
1. I don't want to have to look up complex maneuvers and abilities-- if I have something special, like Martial Arts or something, I should be able to write the quick details on my sheet. The complexity of some of the Gurps MA is an example of this done badly. Basic maneuvers-- feint, disarm, etc should be simple enough that after doing them once or twice, I don't have to look them up again.
2. Maneuvers like feint, disarm, grapple, called shot shouldn't be hideously complicated in play. Yes, maybe there are one of two extra rolls or tests, but they shouldn't bog things down into a mini-game. At the same time, if I forgo my standard action I should have a chance of getting a benefit. That chance should be balanced against the potential reward. That's not always realistic-- disarming can be devastating, so it ought to be tough. As a player I want fun more than I want realism in the combat.
3. There should be some mechanism for coordinated attack or aiding another person. If multiple people fight a target without coordinating, the target should get a penalty. If I forgo my action to aid another person, then the benefit should be tangible. It shouldn't be overpowering, but giving up a possible attack should get me somewhere in the range of a bonus close to half of the original attack.
4. I should be able to do something on my turn. I should be able to move and take an action. That movement shouldn't be too short.
5. Drawing items, reloading, perception checks, etc. should be a freebie. If the system keeps me from doing multiples, I don't mind.
6. There should be a bonus available for clever things. Usually I mean Stunting. If I describe my action to get a modest bonus, I shouldn't have to make an additional check or take a penalty. If I'm going for something bigger, I accept that there might be more tests involved.
7. I like having more hit points or wound levels. If a system has a chunk of hit point-- more than any one weapon strike can do-- there should be a critical hit, status effect or damage bonus system that means we aren't just grinding something to death round after round.
8. I want to be able to make a called shot and have it do something. Called shots shouldn't be insanely difficult to pull off. I also should be able to pull my blow and not necessarily kill someone unless I happen to roll insanely well or insanely badly.
9. The combat should more fast enough that I don't forget what's going on by the time the round gets to me.
10. I should have a decent sense of where we are in the turn.
11. I should be able to delay my action and take it later.
12. Everyone should have someone to fight.
13. There should be some sense of risk from the mechanics itself. By that I mean, I should be worried about damage or status effects. There should be a chance I could die if things go terribly badly-- well, maybe not die, but that I'd get taken out.
14. At the same time the system shouldn't be so risk heavy as to make me afraid to take chances. One hit shouldn't take me out of the fight.
15. If I'm a magic user, I should be able to dish out damage relatively equivalent to a fighter. Some of those effects will probably be not measured in damage, but in my ability to debuff or disable. I accept that the flexibility of magic means a slight trade off, but I should not be significantly behind other characters. If magic costs mana, I shouldn't tap out in a fight unless I've really pushed myself.
16. By the same token, if I'm a fighter I should have some options available to me so I can do more than just declare “I attack” every round.
17. Archers should be able to fire every round.
18. Even in a hopeless fight, I should be able to go down swinging, taking some of the bad guys with me. There's a certain satisfaction to taking out agents and mooks. But mooks shouldn't be just blow-up dummies on the field-- if they gang up they should have the potential to harm me if they coordinate or if I'm stupid.
19. If the combat is incidental, it shouldn't take more than an hour of play time. If it is a larger, set-piece and important battle it can go longer.
20. If I expend limited resources-- like drama and conviction points, the GM should take that into account when describing consequences.
21. The GM should tell me the relative level of damage I've done-- to give me a sense of satisfaction about my action. If something does bounce, the GM should either describe that as a rarity or make clear that some other tactic needs to be applied.
22. If the bad guy is going to escape, I should be able to have done something to him before that-- reducing his forces, getting a wound in, thwarting some portion of his plan.
23. If a combat is narratively unwinnable-- which I can accept for storyline purposes-- the GM should send those signals clearly.
24. I should feel like I'm fighting in a story, not playing a tactical game against the GM. I also shouldn't feel like the GM is changing the situation to get me.
25. If I ask about a combat rule, the GM should be able to make a decision quickly-- unless it is the first time we've encountered that circumstance-- and move on. If we get the rule wrong we can fix it after the fight.
26. Even if I'm a heavy fighter, I shouldn't always go last.
27. The GM should reward clever thinking or clever plans, even if it shifts the GM's notions about the direction of the fight.
28. I should feel all players have equal opportunities.
29. One bad die roll shouldn't make or break my experience.
30. I should be able to have all my basic info for managing my character in combat on the front side of a sheet.
31. Different weapons should neither be too same-y nor vastly different. There should be weapons which are always the obvious choice in all fights, all the time. The same thing for armor. There should be some trade offs (and different initiative values/speed should be worth less in this calculation).
Edited Additional (Nooooo! What about the ice cream?)
32. I should feel like one player is intended to take out the major bad guy and if that's not me, then I don't have a shot.
33. NPCs should bat clean up-- holding strategic points, tying up some of the opposition, and aiding others. Unless there's a plot point involved they shouldn't be overpowering or take care of all the bad guys. At the same time, if we have brought some NPCs to the fight, the GM shouldn't forget them or kill them off to get them out of the way.