Don't know about a lot of the amps you're looking at, but the Shiva is not a high gain amp - no more than a JCM800 really. The Bogner's you might want to look at are the XTC (maybe a bit low gain to be considered a high gainer) and the Uberschall.
It all depends on your budget really. I really like Diezel amps, personally. I'd go for an Einstein (high gain with a slightly more vintage feel) if I had the cash.
Also, you need to look at a Peavey 5150/6505 - even though they are a bit cheaper, they are reasonably well made, and have a classic high gain sound. You may love them !
There's also Engl, which are not priced too unreasonably in the UK.