Eheim also makes the Compact+ series and they are awsome...a bit pricey though. I would also recommend QuietOne series of pumps by LifeGard, very good pumps. ReefFlo, Dolphin and Iwaki all are good...again, pricey. Shop the best for your money. In other words, determine how much you are willing to spend and then go from there.
The sump you have can be made to have an external pump but internal pumps are easier to set up.
Drsfosterandsmith.com, thatfishplace.com, petsolutions.com, marinedepot.com, bigalsonline.com,.....the list is endless. Google.