First off, I'd like to say regarding the original post: I did not start with kits because they are a bit expensive when you don't know what you are doing. I ruined my first batch, but it was a welches' white and therefore no big loss financially. If it had been a $100 kit I would have been more upset.
But since then I've learned things, mostly from this forum. I started doing kits, and I can say it has taught me a couple of things, particularly how to use bentonite, and how to degas properly, especially if you want to follow the timeline in the instructions. But I do kits mainly to drink because it's better and cheaper than store bought wines, so I only kinda consider them "mine" since I follow the script.
Now:
I guess it depends what wine kits you are talking about, but the major brands include name brand yeasts, mostly Lalvin. Also look at the date on the yeast package before buying fresh yeast. In my experience, the yeast expires long after the kit.
The problem (for some people) is that Lalvin EC-1118 is the most popular yeast, and some brands ONLY provide EC-1118.
It is a perfectly good yeast, but some people think it should be replaced by something else.
Steve
I tried splitting my first wine kit into 2 primaries, mainly because I didn't have one big enough to do it all in one at the time. But I thought, I'll try a different yeast in one of them, so I used RC 212 from Lalvin in one, the provided 1118 in the other. The 1118 took right off, but the RC 212 just would not, and after 4 days I took a bit of the must from the 1118 bucket and mixed it with the RC 212, which then promptly took off. I had been checking the SG for those 4 days, and the 1118 was going steadily down, and the RC 212 didn't change.
So, someone later told me that 1118 is used in kits because it may be the only yeast that can ferment those kits. Not sure how true that is, but my experiment of 1 seems to lend credence.