I have a Mark Todd and it's lovely - I haven't had a Thermatex so don't know if they are any better but have been more than happy with the MT. It did acquire a pulled bit of wool on its first day but I guess that's cos the horse was a box rest hooligan - I sewed it back in and it doesn't really show and has never been damaged since (about a year). I bought the neck as well and wouldn't bother with one of those, it's loose and falls down, and just looks a bit daft so am going to ebay that but the rug itself is lovely.
let me complicate things ! I have both and my weather beeta version is better than either !! but that might be coz it fits my horse better . it is also cheaper and you can get them in on line sales quite often.
I've got both, the thermatex has stretched A LOT (great for me as I now use it on a bigger horse than the one it was bought for). The thermatex does tend to hug the horse's shape better than the MT, therefore wicks/dries the horse faster. The MT is smarter and IMO more hardwearing. If I had to buy another I'd go thermatex unless I saw a massively reduced MT... !!
I'd definitely recommend the Weatherbeeta Thermo cell...don't stretch like the Thermatex, don't pick up bedding/hair like Thermatex, and even better I bought two rugs (combos) for LESS than the price of a Thermatex! Got mine for £44.99 each in the sale at Equestrian Clearance.
I have found the Mark Todd much better, they're very smart, you can leave them with it on as they have cross surcingles whihc the thermatex doesn't. I've just found them in general to be the slightly better rug with better value for money also!
In terms of thermal/wicking and overall suitability as a cooler in colder temperatures the thermatex is far superior to the Mark Todd.
However where the thermatex falls down is that the material is very stretchy therefore really only suitable for use as cooler/travel rug. If you want to use it for layering it is rubbish, really pulls back and puts pressure points over withers. It is also too warm for the summer (although Thermatex do a great summer weight rug too).
The Mark Todd is thinner and from direct experience with both not as good at wicking. It is however a far more versatile rug and is better multipurpose.
If you are prepared to spend some ££ have a look at the Landsdown equivalent, just as good as thermatex but with the versitility of the Mark Todd.
If I were on a budget I would buy Mark todd over Thermatex, if I wasn't I'd buy Lansdown
I love my mark todd rug, and used it alot on G horse. However, it is too small for Lucky, so am on the look out for another of the same type, and at the moment am torn between another MT or one of the shires ones! I wont get a thermatex as they cant be used as "proper" rugs
I love comfort zone rugs aswell, but their sizing is a bit strange.
I have a MT coolex rug, and an exercise sheet, both have been washed often and still look like brand new. I did have a thermatex, but it has stretched beyond all usefulness now and even though I bought it as a 6ft6 it is too big for my dinasour size TB!
I've never had an MT but I would suggest if you go for a Thermatex , get one of the covered variety ,they don't stretch out and bits don't stick to them.