I've found the Holtons to be heavy and stuffy on the whole, but if you really, really search you can find some that blow freely. FYI Holton-Farkas is the name of the mouthpiece.
I put my money on Yamaha. Disclosure here, I've been playing on a Yamaha 667 for the past 32 years. I prefer the 667 (Guyer wrap), but the 668 (Krupsie wrap) is good as well. I also recommend the 567 too. The 567 is the step-down from the 667.