Arnold Zwicky talks about zero-tolerance writing style rules and, in particular, sentence-initial however.
I read his essay with a certain amount of dismay. You see, what people apparently are taught to is use however only internally to a sentence, as a conjunction between independent clauses, and to use but sentence initially.
It turns out that I do pretty much the exact opposite of that. I only use however in sentence-initial position, where it sounds like you've completed a thought and are now, after due consideration, offering a contrast; the length and weight of however helps in that respect. Used internally, it sounds like a run-on sentence to me. E.g. "Bruce is a brunet. However, Bruce's sister Briana is a blonde." instead of "Bruce is a brunet, however, Briana, his sister, is a blonde."
Similarly, I never use but in sentence-initial position; it sounds too abrupt, and I feel it needs to continue on from the thought it's contrasting against. The shortness of but seems to make it more suitable as a linker between continuous thoughts. E.g. "Barry Allen and Hal Jordan had very different personalities, but they were still best friends." instead of "Barry Allen and Hal Jordan had very different personalities. But they were still best friends."
Fortunately, this is a case where it's really a free stylistic choice, so screw 'em.
UPDATE: More from Zwicky here.
"Barry Allen and Hal Jordan had very different personalities, but they were still best friends."
See, that's a grammatical error. It should read "Barry Allen and Hal Jordan had identical generic DC Silver Age Hero personalities, but they were somehow imagined to be different people."
I would argue that by the Bronze Age, Barry and Hal had detectably (if, indeed, often inferentially) different personalities.
Indeed. I could see Hal Jordan having athree way with Carol and Iris, but I could only see Barry having a three way with Iris and Hal.
Barry was clearly smarter than Hal, though, because the guy who told Hal he wasn't doing anything for the Black skins should have been told that when Hal saves the planet, he's doing ti for everyone.