What does very long battery life mean to you? I don't do multi-day rides where I don't have a chance to charge in between them, so even an 8 hour capacity will be "long" to me.
The "simple" want for only distance and speed probably won't get you as good a device. A device that will be very inexpensive and have just speed, distance and a few other features will be made on the cheap with respect that they are probably made with little mean time between failure concerns.
Stick to Garmin, Wahoo or Lezyne if you want a decent GPS device that gives you speed and distance along with a good smattering of other features. Maps and navigation do add complication, but Garmin has Edge devices with no maps. They'll still give you a lot even without maps.