In Dash Navigation Units???

Hello fellow Prius Owners.... I recently sent in my car for a few works to be done here and there and I think it is a good time to get some upgrades done... The first one on the list is a Navigation unit.... I am only familiar with Ottonavi and Rosen but i am not much familiar with how good the units are... I used to use a Garmin Nuvi 1450 unit till now and it has kinda died on me too.. So using my phone which is good but i want a unit so that i can worry less... What would you fellow owners recommend? Any experiences..

PS: I will be doing the install myself so I am also concerned about the ease of install.