I'm rapidly running out of choices, seeing as Dunlop have pulled my preferred SP9000s, which are the tyre I always kept coming back to on the Omega, and always regretted trying other tyres.
For the ones I've tried on the Omega, this is the order I'd put them in - remember, my needs may be different to others.
Dunlop SP9000/SP9090 (MV6)
Conti SC2 (MV6)
Conti SC3 (MV6)
Nexen CP641 (Tractor/TB2)
Dunlop SP200 (Tractor)
--------------------------------------
Dunlop SP3000 (MV6)
Pirelli P6000 (Tractor)
Khumo (cant remember type, sorry) (TB1/Tractor)
Michelin Pilot Sport (Tractor/3.2 Elite)
Avon ZZ3 (Tractor)
Those above the line, I would have again, those below, I really wouldn't.
I do get to drive a fair few Omegas, though as they belong to other members, I obviously would test the tyres as much as I test my own. But notable very bad ones include Chrisgixers at Asheridge (Faulkens?) and Tunnie's 2.2CD beyond he hanged the tyres (Goodyear?). Cant remember the tyres beyond make, hopefully they can fill the gaps?
The ones that impressed me were the budget Nexen CP641 on the tractor (which had a fairly viscous power delivery, and often lit up the rears

). Stonkingly good in the dry, every bit as good as some of the premiums (maybe not the SP9000s), and OK in the 'normal' wet. Downside, utterly leathal ditchfinders in VERY heavy fresh rain on greasy roads. Touching cloth does not even begin to describe a couple of moments I 'enjoyed' in the tractor in those conditions. Fun though.