I can not say, I tried them all. Not at all. But I'm working on it. :-)
I'm agree with the fact, that hand-made brands may not be around forever... and it si too bad. Worst of all it doesn't just apply to the hand made ones, but some manufacturies cutting down on their colors as well...or just changing their formula... Holbein would be a good example of it. So, I would say - it is very good idea to keep in mind what you like the best AND what you may like use for replacment of this "very best", it if is just not available.
Like probably everybody I started from something what was around and was cheap. It was enough to get me interested. Long time ago my first ever pastels was Russian set of Yarka. They have their limitations and I can not stand their greens, but on other hand blues and pincks and aslo earth tones are nice and useful.
Then I tried Rembrandt. So far I would say that would be my last choice, if nothing else is available. It is the only brand, what has no light in it at my opinion... They all dull and flat. Just my 2 cents, but I'm not impressed.
Surprisenly, I like Nupastel. Goes great us first layer, or like fine detailes for the last one. Great work horse. Once again - no usefull greens, or very few...
Now about favorites... Holbeins. Great medium-soft pastels. Very even from color to color, no surprises here.. "this one is too soft, this one is too hard", nothing like that. Economical, works well on any surface. Just love it, period. Could use more colors and (the worst news), how I understand company totally changes a formula for their soft Holbeins. Now they are water-soluble and round. So when old sets are gone, they are gone.
Schminske. Perfect. Just perfect. No other comments. Love from first touch.
Terry Ludwig. Long live live, Terry! We all need you! You came up with the great stuff! I only have few hand picked colors and they are one of my very favorites.
Unisons. Absolutely great stuff. Feels somewhat hurd, goes like a velvet. Amazing. I only have a Special collection and one of their greens, but with occasion sure will get more.
Giraults... I only have some hand piced selection of greens... Wish to get a full set someday. Yes, they are just as good, how they say.
Art Spectrum. Rated about the same, as Rembrandt. yet, it is totally different stuff. Much brighter colors with a lot of light in it. Have great darks and great lights. I personally have so called "Marine set" of 40. Like them a lot. Good for Seascapes and.. landscapes too. Goes well with another brands.
Winsor and Newton. I don't like standard selection in teir small sets, but quality of pastels is good and some colors are very usefull. I belive some stores have it in open stok now, what is a great news. They are softer then Art Spectrum and not so bright, but very usefull. Definetelly better then Rembrandt (at my opinion).
Great American... I just tried one of their colors. If the rest feels the same way, they are one step away from Schminske... I'm not sure if it is step up or down!
Sennelier... Once again, surprisenly, I'm not big fan of it. If we talk about "soft", I like Schminske much better. If we talk about colors... I still like Schminske better. Plus they are very uneven from color to color, some earth colors are hurd as a rock and this brand is not the best with layering too. Maybe I'll change my opinion when I'll be more profission with pastels, but so far I have a problems with this brand, just like with Rembrandt. No offence to anybody.
Mount Visions. I have 50 colors. Hand picked set of 25 and Tunderstor Grays. Great pastels with good price. Like them a lot.
Richeson hand made. I have a small set of those. Very nice. Nothing to die for as for my consideration. However it is a SET we are talking about. I'm pertty sure, if I would be picking from open stok, how I love to do, I would be much more impressed. I generally often don't like colors what comes in standard sets (unless it is a full set, what I have only in Holbein for both - soft and oil pastels). They works for me just perfect, espessially because I like to work on miniatures.
Pan Pastels - great addition to the rest of your collection. I only have 4 colors what I can use the most and yes, I like them, but no, I wouldn't use it as an only brand for no painting. Some things will be missing here... I'm totally in love with applicators for those pastels, never tryed anything for blanding that works so great!
Kooh-I-Noor... As the rest of art supply of same brand - good and honest. Somewhat soft, but not too soft. Interesting to try. Do not try to use those with water... doesn't work at all.
And of course pastel pencils.... I personally like them and have a planty of it sitting around on my shelves.
If I would have to choice totall favorites from everything I tried:
Girault, Terry's, Schminske, Great Americans (even I don't have them!), Holbeins and Unisons and of course - Mount Vision. Everything else I can survive without, but doesn't mean it is not going to work!