I use Schwalbe city jets on my hybrid, and I've been happy with them so far - mine are a 32c size though - these tyres have a slight tread and a reflective sidewall.
I used Panaracer Pasela 28C tyres on my old road bike, and thought them really good - they have a slight tread on them, and seemed very resistant to the p* fairy. They do look a bit old fashioned with their gum wall sidewalls though.
If you want to go slicker than that,
Wiggle had a decent deal on wire on Conti Ultragators, 2x tyres and tubes for £36 ish. I'm in my second week of using them in 25C on the road bike on my commuting wheels, and am happy so far.
My SCR2.0 came with Kenda tyres, and I had to buy more tubes just to keep being able to ride the bike in to work (I invariably had two to repair at the weekend, if not all four, and never carried less than two tubes with me on a ride). The final straw came at 300 or so miles, where the bead on the rear tyre began to separate from the tyre carcase (once this opens a wide enough gap, the inner tube will forces itself out between rim and tyre, and blow up quite spectacularly).
If you need heavier tread, I can't really help, as my bikes are ridden more or less solely on tarmac... I've also just realised that I'm assuming your wheels are 700c as well!
Edit: Both the city jet and the gators come in 26" sizes - the City Jets are available in a tyre and tube set for £34 ish on Wiggle.