Before we go any further, I hereby bow down to those who mix their own glazes. It takes a knowledge of chemistry and a patience that I simply don't have and don't desire to learn. It is an artform in and of itself.
That being said, she asked me my favorite brands and since then, I've thought that I might have to backtrack on my initial answer. I initially said that I love Coyote glazes. But then I made all sorts of exceptions - this one turned out ugly, that one doesn't work the way I like, etc etc.
I think I have tried just about every brand of glaze out there. I'm constantly on the hunt for new colors. I number the back of each test tile I make and I'm currently up to number 82, so yes, I've sampled several. I think I currently have about 30 different pints in my cupboard. Several of them are only there because I didn't like the color, but can't bear to throw out useable glaze so I keep using them for the insides of mugs and stuff until one day, thankfully, I'll run out and be able to throw it away.
So I started thinking about if I had to choose only a handful of glazes to keep in my cabinet, which ones would they be?
All of the following observations are based on the results of my medium size kiln (I think it's an 18 inch hexagon, about 3 feet tall, inside dimensions) with a kiln sitter. I put the little cone it and when it melts, the kiln turns off. No soaking, no holding, can't really do that. I've tried using cone 5, cone 5 1/2, and true cone 6.
If I could only use 5 glazes they would be:
1) Albany Slip Brown, Potters Choice. Quite simply, it just works. It's a beautiful color that breaks gold. Looks good over texture and creates its own visual interest if no texture is present. Works the same on cone 5 through cone 6 and doesn't run all over my shelves.
2) Blue Rutile, Potters Choice. Like above, it just works and behaves properly at just about any of my temps. It's a blue that will never go out of style. It needs to be applied thick or you get a brownish black. It does run a little bit (due to being applied very thickly) but you tend to get kind of a bump blob of glaze under the handle of a mug rather than a whole bunch of glaze all over your shelf.
This might be replaced by either Coyotes Mottled Blue or Mayco's Blue Surf. Both of those have brighter blues but I haven't used them enough to be able to predict the outcome when I use them.
3) Blue Hare Fur, Clayart Center. Everyone needs a reliable black. This has blue undertones when applied thick. Another really good behaver in all temps. And it mixes with other glazes REALLY well. If applied over blue rutile, it will exaggerate the visual flow of that glaze without changing the color. If applied under albany slip brown (and some others that I've tested it with), it creates a whole unexpected effect.
Don't have a sample of it by itself, but here it is first under, than over stellar rust. 
4) Clear, Continental Clay. I do a lot of agateware so I want to see the color of the clay itself. It was hard finding a good clear. They tend to be milky or bubbly, or kind of clump up on the pot. I've found continental to be the best of those I've tested. Works at cone 5 1/2 but looks even sharper and clearer at 6.
Hmmmmm, I guess I only had 4 must haves. Ok, here's a list of some new glazes that I've done a test tile for but haven't tested extensively and therefore I can't get them a definite "must have" title yet.
1) Hellfire Red, Kentucky Mudworks. If this one works out, it will shoot high on my list. It's like a deep brown but with a shimmery pink floating on top of that brown. I did the test tile at cone 6 and it's beautiful. I did a firing at cone 5 1/2 where I used it and I kind of had to search for the shimmering color. It came out mostly brown. So I think it needs that extra heat.
2) Deep Firebrick, Potters Choice. It's a deep, non cheesy, brick red. Shows texture pretty well.
3) Stoned Denim, Mayco. Seems to work well, a really nice flowing greenish blue over a black base. Very nice over extreme texture but does need to go on thick so it can obscure softer textures.
4) Merlot, Clayart Center. It's a lovely purple and leans more to the burgandy/red side of the purple spectrum. Goes gray when thin so if applied medium, it's a showcase for texture.
And here are four that I will never ever ever buy again and kind of hope my leftovers accidently fall into the landfill.
1) Sunrise Shino, Coyote. Cedar Shino can go with it. I've tried it at all temperatures and I just get pepto bismal pink. Flat, thick, blech. But sometimes you need a pink which is why I haven't just thrown these two out.
2) Chun Red, Laguna. I just got a mess. No red, just ick. Threw it out.
3) Eggplant, Coyote. It's matte, kind of an olive green the goes purple when it reaches a hot enough temp. When fired at cone 6 I got more purple and it was more acceptable but just too unpredictable. At cone 5, it came out a really rough texture and just kinda blue.
4) Steel Gray Shino and charcoal satin, Coyote. Came out matte and flat which I don't like. But when I fired one or the other at a real cone 6, I actually got a smoky effect that had some depth. Will have to experiment with the hotter fire more, but if all else fails, out the door they go.
And a few parting notes.
1) Hyacinth, Laguna. When it works, it's the most beautiful glaze. It's a purply, smoky, wonderful colors. But when it doesn't work, ick. It runs if fired too hot. It seems to get some sort of grit that floats in it and when fired, sometimes that grit is just embedded and creates little sharp points (especially prevelant inside mugs for some reason) or it just seems like it burns. I will not include this in cone 6 firings anymore because it runs and ruins shelves pretty much every time. But I'll keep trying to make it work at cone 5 1/2.
2) Coyote glazes in general - I have a feeling that as I see more of them fired to a proper cone 6, I'll like them more. They seem to be coming to life more when I fire them hotter. But I am concerned about Red Gold. It's on so many show pieces for Coyote and yet I'm just not getting the same results. I'm getting a flat brown with runs that kind of glob yellow. I was really looking forward to trying this glaze and I'm very disappointed. I think it must require a hold time or something that I just can't do. And Pam's Blue - I had given up on it because at cone 5 1/2 it was just a flat blue and gray mottled glaze. But when fired at cone 6, it became this wonderfully streaky, full of effects glaze. I'm now considering buying more and trying the Pams Green when I had previously decided not to get any more.
3) Spectrum glazes - I won't buy them anymore. They run like crazy even at cone 5. Texture Oasis would have been lovely but I just couln't make it work. I even did an 8 inch tall planter and the only glaze was a one inch stripe of texture oasis near the top. And it still ran all the way down the pot and onto the shelf.
4) Antique Iron, Opulance. Very nice at cone 5 1/2. Gets some nice variation as the blue and a touch of green kind of burst out of the brown over texture. But fired at cone 6, bye bye kiln shelf. Much more color bursting but it will melt right off your pot.
5) Clayart Center Brand glazes (from a store in Tacoma), these are not the most flashy colors or anything, but they are solid good glazes. I use powder blue, evergreen, and of course blue hare fur. These tend to be solid colors but they behave well and tend to mix with other colors to new effects. But in their pints, they are really thick. Every time I use the evergreen, I replace what I took out with some water to thin the remaining, and I still have a completely full pint that could use some more thinning. I'd say I've used about half of the glaze originally in that pint and replaced it with water and it's still too thick. Then again, more for you money!
And what's really sad? This isn't even all of the glazes that I'm CURRENTLY using. *sigh*
