dtgreene: * I don't like automatic reactions, at least not as a default ability. I don't like the fact that someone gets an extra turn just because of something the opponent decided to do (this applies to both counter-attacks as well as things like attacks of opportunity). Also, such mechanics might easily favor physical attacks over magic, or if spells aren't countered, might sometimes favor the reverse.
misteryo: I do like them. Mainly because attacking someone should be kind of risky. In Darkest Dungeon, several characters have an action that activates "riposte," which is a reaction attack. It comes with a reduced damage and some other mitigating factors. And it works well. I think this is a matter of working out the right balance, rather than the idea being just good or bad.
In the context of a tactical battle system, there is an inherent risk in using a melee attack: To use a melee attack, you (generally) have to go right next to the enemy. This means that, if you don't kill the enemy, the enemy will be able to attack you on their turn, putting your character at risk.
Dungeons and Dragons 3rd edition has a particularly interesting example: If you move right up next to the enemy and attack, the enemy will, on its turn, be able to make a full attack against you. Assuming a base attack bonus of at leastl +6 (for a Fighter, this means being at least level 6), or if dual or multi wielding (some monsters can make more than two attacks), this means having to deal with lots of attacks from the enemy this round.
In a non-tactical battle system, attacking means you don't get to defend or heal this round, so there is still this cost of not attacking. For example, if we look at Dragon Quest 2, where there's a reusable item that heals the user for free, if you are low on HP, you might not want to attack. On the other hand, there are some enemies you might not want to leave alive, either because they can heal (the final boss can heal itself fully, for example), or because the enemy can do something nasty (like casting a spell that can instantly kill your entire party).
dtgreene: * You mention the game showing the next 8 turns. That, however, doesn't work well if you're fighting, say, 396 berserkers; in that case, even if only 3% of them get to act before your character's next turn, your character won't appear in the turn order listing.
misteryo: Yeah. This system would not be suitable for very large battles. It also wouldn't be suitable for very small battles, which is why I stipulated minimum party size of 4. And that doesn't bother me either, because battle systems in general are not very scalable. The size of battles tends to be fairly consistent within one game.
Different sized encounters can lead to good variety. I can think of a few games where encounter size varies:
* In Bard's Tale 3, you sometimes encounter dozens of enemies, but often those enemies die easily to group spells. On the other hand, occasionally you might encounter more powerful enemies who don't die so easily, and there you might want to use single target attacks (like melee attacks or death spells) so that the enemy dies faster.
* SaGa 2 is interesting. Some areas tend to give you small encounters, where physical attacks (especially if you have a robot with high agility) can end the battle quickly; however, you might not want to end the battle quickly so that your humans and espers (mutants) get a chance to increase their stats. On the other hand, some areas have you fight hoards of enemies at once (and in the DS version, there are chain battles where you fight even *more* enemies, perhaps as much as 50, in one battle), and there you want to use magic to kill lots of enemies quickly; those battles are very good for getting money (not XP, which doesn't exist in this game). Then you have bosses; mostly single enemies, and the later bosses take half damage from physical attacks, somewhat balancing robots and spellcasters.
Also, I find that battle systems with positioning tend to flow better if you only have to control one character; Ultima 4 is a great example of this. In Ultima 4, the game flows best if you don't recruit any allies; if you do, battles take a lot longer. (It's worth noting, however, that you can't actually beat the game without a full party; you can, however, pass all the game's combat challenges solo.)