Which Would You Prefer? (And Why?)

[Childe]

General question, looking for player preference, not specifically with regard to edition wars:

"Swift or Immediate or Next Turn's Swift" tradeoff between Swift and Immediate actions
OR
decoupled Swift and Immediate actions (1 of each per round for free)

[Keldar]

Decouple.  Mostly for accounting simplicity, no need to remember what you did between turns.  Sometimes that can be a huge amount of time if someone is slow or the pizza shows.

[TenaciousJ]

Option 2 with more options for characters to take advantage of the extra actions per turn.  Tome of Battle classes are a good baseline.  Plenty of immediate action counters with stance options on the swift with a couple of boosts to compete with the stance switches for the swift action.