I'm thinking about trying a low carb lasagne and I notice people using many different veggies in place of noodles.
I have seen:
eggplant slices
zucchini
green beans
cabbage
spaghetti squash
etc!!
Has anyone tried different ones and if so, which one do you prefer?

I've used cabbage, eggplant, and zucchini (alone and in combination).

I don't like large eggplant, so I only use the long, asian eggplants.

In my opinion, cabbage leaves best duplicates the lasagna texture. Zucchini I found too watery to use as the "noodle" substitute, but cut into matchsticks it makes a nice portion of the filling.

I've also made a lasagna type dish without any noodle substitute. I saute all sorts of yummy veggies (andy or all: onions, bell pepper, celery, carrot, eggplant, zucchini mushroom...) with ground meat or my ground meat/tvp mixture, along with homemade or jarred spaghetti sauce.

While that simmers, I make my egg/cheese mixture.

One egg, a large container of cottage cheese, ricotta (or a small container of each) some shredded asiago, parmesan or romano.

I line the lasagna pan with foil, pur in the cheese mixture. Top with the meat/veg/sauce mixutre and top with a little bit of shredded cheese (usually mozarella and asiago or a packaged italian blend).

I recently had one made with eggplant slices. If zucchini was done the same, might not be so watery. The slices were placed on paper towels and salted, left a while, then turned over and done again. The lasagna was excellent, and the eggplant had a nice texture.
I used spaghetti squash quite a bit when the rest of the family is having spaghetti, they now prefer the squash!.

I just had this last night - I used summer squash that i had left over; i had originally sliced the summer squash and grilled them on the grill. Last night I just chopped them up (using medium size chunks) but I'm sure you can keep them sliced long-ways. I also used a low carb pasta sauce and it was wonderful! I was very pleased...had the left overs again tonight!

Personally, I love lasagna with zucchini strips in place of the noodles. Zucchini has a mild flavor and softens nicely. It is perfect for me!

What if you used the recipe for the cauliflower pizza crust and used that as a sub for your layer of pasta?

There is a noodle-free version in George Stella's Living Low Carb cookbook. It is really great, too. I like having the veg "noodles", but the meat cheese and sauce one is wonderfully rich.