If you're wearing leather, don't rush out and buy something expensive. Leather is reasonably waterproof as it is and so shouldn't need 'good' waterproofs on top of it.
Try the local ex-army store for some cheap waterproofs. I don't know about jackets so much but the pair of leggings I got are superb. Green nylon with a rubber backing. They have stood up to one and a half hours riding at 50-60mph in extremely heavy rain (Going to Morecambe just before the TT) and didn't leak a bit (shame about my boots, gloves, jacket though) My only gripe about them is they have huge flares (to get on over boots) with press stud adjusters to tighten them up once on. When you use the press studs they ride up your leg and dump water in your boots. The alternative is to look like a reject from the Bay City Rollers.
> Kevin > I looked at a Rukka jacket and trousers a few days ago and was not impressed! - it > seemed very thin and had virtually no crash protection.You what? Did you look at the Rukka RVP stuff or just the lined waterproofs? When I did my dutiful vegan tour the Rukka RVP was definitely the best I saw skidwise (Bullson included, though I didn't find any IXS, or Spidi). However, I didn't buy one & have been wearing dead animal skin instead. If your friends aren't too vocal you'll get over the shame, & if you buy a decent set, you'll only have to buy the one set.
I had a leather but needed a waterproof. I was going skiing and planning other outdoor activities. (behave!) The answer: Sprayway GORE-TEX clothing. Expensive @ 170 odd bucks for the jacket but 100% waterproof (guaranteed 5 years), easy wash (just stick it in with everything else), bright colours (if you like that sort of thing), breathable (summer use), packs small, made in UK and big enough to go over everything else. I invested in the Polartec lining for non-motorcycling activities which makes it the best all-round piece of clothing i've ever bought. Available in Camping shops.