Bookshelf speakers that sound good on a SHELF or SIDEBOARD

Focal Aria 906 on ISO Acoustic Aperta 200 stands would be my highest recommendation anywhere near that price point.

Get sealed cabinet speakers or good headphones. 

I would recommend a front ported speaker.....or sealed acoustic suspension like Helo mentioned,  but not many small speakers aren't ported.

In this same situation I have used both Rogers LS3/5a (also available from other manufacturers as noted by yogiboy) and Allison CD-6 (available on the used market from time to time, but you must be patient). Price points are very different including the variations of the LS3/5a. ZuAudio also makes a couple of speakers for this purpose - Cube and OmenBookshelf; but I have not heard either of these.

The LS3/5a and its successors have been the classic choice. For years I happily used the LS3/5a as my desktop speaker, and only recently replaced it by the far superior Harbeth P3ESR. Both of them have suffered a bit from bass boost as a result of the proximity of the desktop surface. I have cured most of this by raising them some 8 inches using little isoacoustics stands. In my case that had the additional advantage of bringing the tweeter up to ear height.
The remaining lump I cured with an equalization graph in REW and uploading that into the Equalizer APO software on my desktop PC (used as a source). Traditional tone controls will also do this, to some extent, and not as precisely. I do not think you can avoid using a bit of equalization, and the more precise the better. But with it, you should be fine.