jQuery 1.x is recommended over 2.x due to lack of IE8 support in the latter. If you don't have IE8 traffic on your site, you can safely go with 2.x (which isn't that much smaller to begin with).
I thought that was true, but checked a few months back and the advice seemed a bit more equivocal than that:
> So, here’s the TL;DR for version 3.0 of the jQuery API:
> * If you need support for the widest variety of browsers including IE8, Opera 12, Safari 5, and the like, use the jQuery-Compat 3.0.0 package. We recommend this version for most web sites, since it provides the best compatibility for all website visitors.
> * If your web site is built only for evergreen leading-edge browsers, or is an HTML-based app contained in a webview (for example PhoneGap or Cordova) where you know which browser engines are in use, go for the jQuery 3.0.0 package.
I personally currently need to support IE9 which I wouldn't class as an "evergreen leading-edge browser". I was hoping for a more in depth compatibility chart that named specific versions.
