Just my 2 cents but if it was me I would be tempted to get something like a Stirling Finest Badger Fan brush, about £40 and a great entry into badger brushes. I have one and it is cetainly comparable to many brushes several times its value. Whilst I love using my Shavemac, I enjoy my Stirling as much.
Synthetic is another good shout, especially the Razorock brushes which are fairly cheap and great brushes for the price. I prefer their handles to the Fine brushes but the hair is essentially the same.
I don't see much love for horse hair on forums but if you can put up with a little stench and scratch for about a week or two, you'll be rewarded with a fantastic brush that softens very well and is a perfect hybrid between a badger and boar. I use a Vie Long 40503 and it is fantastic, I wish I had bought one years ago. I quite fancy another.
I also give another vote for the Vulfix Grosvenor 404, a cheap mixed hair brush and fantastic. Worth the price for the handle alone!