Hi C.,
I am in the same position you are. After doing a ton of research (and consulting my "Baby Bargains" book), I ended up buying a gently used Britax Marathon carseat off of Craigslist that was a two years old for one car. For my second car, I am getting a Sunshine Kids Radian 65 from Bed Bath and Beyond. If you place an order in the store for an item online you can use one the 20% off coupons that come regularly in the mail. This made that car seat about $170. As others have mentioned, this is a narrower car seat and it folds to 6.5" flat, which makes it more easily transportable in the event you need to fly somewhere.
I had also looked at Cosco Scenera. They were rated well but a friend told me that her daughter wasn't that comfortable in it for long rides as there is very little padding. But if it were in a second car and not used for long rides, it could be a great deal (between $50 and $65 depending on the seat cover, it seems).
Out of the seats you listed, the Evenflo Triumph had gotten the best ratings, based on what I had read.
(Good job on the cloth diapering, making your own baby food and breastfeeding! I'm doing all of that as well! Nice to see like-minded parents out there!)