You left off the RS28, which is almost identical to the 9950 (guess who makes the Dayton driver). And really it is so personal preference and application specific no-one should really recommend you anything. If you like silk better then of course buy the silk Seas, if metal either the Usher or LPG will be fine. The Usher and Seas play a lot lower in frequency cleanly though, so I'd use a mid that can play higher with the LPG and then of course mount them as close as possible to each other. If these are going to be mounted off axis then by all means make sure you note the off axis response and do worry about extra reflections when selecting as well. If I had to pick and I were you and they were mounted within 20 degrees of axis I'd grab the Usher for metal or the Seas for silk depending on your preference. (you may find in your Escort though that having the tweets completely off axis sounds better, just experimentation will tell).
Don't worry about tweeter efficiency, just throw a good 50w amp on them and any of the above will be fine--you probably will rarely be putting more than 10w into anyways.
As with any install of any speakers in your car, the actual installation is really the deciding factor on how they will sound. This is especially true with DIY sets since you are at liberty to choose what frequencies go where in your car and to what driver.
