The only bike computer I have experience with is the Garmin Edge 500 and it is great. I have it paired with the cadence and speed sensor and it works really good . To keep the cost down I ordered it re manufactured from Garmin and got it over half off with the same 1 year warranty. Highly recommended.
I use the Wahoo Blue SC. It transmits both speed and cadence via Bluetooth or ANT+. The data is transmitted to my phone via their app. It is very user friendly and customizable. My phone is mounted to my bike with a RokForm Pro Series Bike Mount. I have a Samsung Galaxy 7 Active so I’m not concerned about the dust, moisture or impact. You can transmit the data to Strava and a bunch of other apps directly from the Wahoo app or download the gps data. I also use the Wahoo TICKR Heart Rate Monitor. It works well for me.