我这个J1在哪办好？

本人在英国读博士刚毕业，去美国做博士后，我应该在伦敦签好呢还是回国签好呢？

说下我曾经的一个情况：
两年前我准备从英国去美国开会，在伦敦大使馆签证但是被check，直到会议日期过了
才给我发信说：
“Unfortunately your travel dates have now passed, however we may be able to
issue your visa if you wish to travel for the same purpose at a later date.
...”
于是我又找了一个在美国的会，但可能是时间隔得比较远，大使馆回信说你这情况等会
议日期前2个月再重新填DS157申请吧，但是申请费就不用再出了。我于是提前3个月申
请，但是东西寄过去就一直没消息，直到会议日期又过了来了一封和上面一模一样的信
。于是我就不理这事了，直到现在。
以上申请是用旧护照办的，现在我旧护照快到期了，于是最近在伦敦中国大使馆办了本
新护照。

求高人指点：
1.我这个情况是在英国签好呢，还是回国签好呢？那个容易过？
2.我去签证，他们肯定会要我的旧护照，我那段经历是主动交代（并附上当时的邮件）
好呢，还是签证官不问我就不提呢？

PS: 在美国驻伦敦大使馆的网站上有这么一段：
I'm already in the United Kingdom, why can't you issue me a visa here?

The consular officer who evaluated your application is accredited in the
United Kingdom and is only able to assess your ties to the United Kingdom.
It is not possible for consular officers here to be experts about all other
countries, or to understand any social or economic ties you may have to
another country. Nevertheless, even though your application has been refused
in the United Kingdom, if you are here temporarily you may be able to
qualify for a visa if you applied at home. Consular officers in your home
country are better able to assess your situation there.

我现在感觉我无论是和英国还是国内都没什么ties呀，怎么办？