I like the idea of wintersowing, but for all practical purposes I suspect that I would end up killing anything I plant that way - I'm not great at remembering to water outdoor containers. Also, after a LLONNGG winter here, I'm always keen to actually tend my plants . . . I check every morning for little sprouts, spritz them with the water bottle, do the happy dance when I find a sprout. Really, that's half the point of starting seeds for me. I've read a bit about wintersowing before, though, and I think if you're short on time and energy to invest in your plants, it's a fantastic idea.
I like little plastic mini-pots and the trays with separate spaces for each plant. I reuse them every year, and I don't disinfect them (although I do leave them outside in the freezing cold garden shed) and so far I've had no problems at all with seedling diseases. My SIL says I have a particularily green thumb, but everything I try mostly just seems to work.
There is one exception, which is the coir (coconut fibre) pots. I got these as an alternative to peat pots, because peat is a non-renewable resource (and I live near peat sources, so they're pertinent to me) and coir comes from a waste product from a renewable resource. On paper, it's a great idea . . . well, except for transport costs. In practice, they were pretty bad. The squash, peppers and tomatoes that I started in them grew slower in under the grow lights than the same varieties in plastic pots, inches away. Once I put them in the ground, the plants from coir pots were so slow that the direct-seeded squash outpaced the ones from coir pots (the ones from plastic pots were the best). I don't know if the root systems just got too dry while they were still inside, which is possible (our house is extremely dry in winter). I know that when I put them outside, the roots had a lot of trouble penetrating the pot - at the end of the year, when I pulled up the most stunted plants, without exception, they all had a little root ball still nearly fully contained in the fully-intact coir pot.
So not a suggestion for what to use, but a suggestion for what NOT to use, I suppose.