Usually if there's not an unacceptable RINO who MUST be stopped in the primary, I'm inclined to vote for whoever I think would be the best choice, even if they stand little chance of winning. In that case, my choice would probably be Bill Johnson (I agree he seems to be the only solid Reagan Republican in the race), though at this point it would be little more than a throwaway protest vote against the two "main" choices.
IMO, Grayson was expected to easily win the primary as the big name statewide official, so it's internal problems with his campaign that are causing him to struggle with Paul. The problem now is that Paul is portraying himself as the true conservative choice and Grayson as a moderate establishment squish. I don't think that reflects reality, as it seems to me that Grayson is better on social issues (right to life, traditional marriage, etc.) and national security issues (keep gitmo, support the Patriot Act, etc.) than Paul. But Grayson isn't communicating this to voters and Paul is deliberately being vague about his stance on those issues. Paul is probably the stronger candidate on economic issues like abolishing the income tax, returning to the gold standard, etc.
The main problem I have with these candidates backed by the Paulbots is often the bots themselves. They tend to hijack the GOP message in November and make everything a referendum "Dr. Paul's rEVOLution", sending any Republicans who don't think Ron Paul walks on water to the back of the bus. This tends to narrow their candidate's appeal (Chuck Baldwin had the same problem last November when his conservative third party campaign was engineered to appeal solely to Paul voters, though his background actually fit with Mike Huckabee, Fred Thompson, and Duncan Hunter voters more). And I'm the Peter Schiff campaign in CT is suffering from the same problem. Schiff is the consensus conservative choice but the Ron Paul fan club wants to make everything about Ron Paul.
This could hurt Rand Paul's chances of winning in November (as Field noted he's using daddy's network of support and fund-raisers to propel himself ahead), but I don't know if it would be a fatal blow to his candidacy.
Thank you for your more level-headed analysis here.
If Grayson is a true conservative, he'll have to campaign as one.