I use a Garmin Dakota 20 because of its versatility I use it for everything from biking to camping. I use on mountain bike and my road bike as well as for hiking and camping. You can purchase additional maps but I haven't needed that level of detail, the supplied map is fine. It can also be used in car with turn by turn directions if you want. It has the micro slot near for extra maps too that you can download for free on-line. Many of the maps are topo and very detailed 24K versions. It's ANT capable so I have speed, heart rate and cadence sensor for that. There are newer models out there such as the etrex models so you could probably get a Dakota for 150 or a new Garmin model for several hundred such as the etrex or Montana series. I like mine because of the versatility and its about the same size of the bike specific models. It also takes batteries which is handier than a recharge model. Good Luck on whatever you choose.