I use a Rimowa Salsa Deluxe business trolley. It just fits.
Note that this is a half-height trolley....there may be full-height trolleys that fit but flight crew will often eyeball a full-height (even if it fits) and force you to gate-check it.

Here's a more detailed answer with photographs of the suitcase in an overhead.

http://travel.stackexchange.com/a/58599/30408