Here are few bike computers we are using in the group so we know that they are reliable. Of course this list is not exhaustive.

Garming 530

It has buttons to navigate the menus. It easy to sync with Garmin Connect and Strava (with additional applications). It lasts about a day's ride depending on what setting you have on. They are some available on ebay from time to time.

https://buy.garmin.com/en-GB/GB/p/621224

 

Garmin edge explore 

It uses a touchscreen to navigate the menu with a large screen. It also provides good mapping and route following. It doesn’t have more sophisticated options like live Strava segments or power output.

https://buy.garmin.com/en-GB/GB/p/611996 

 

Hammerhead Karoo 2

It has a very good touchscreen, inexhaustible customisation and programming options, but is not as durable as one would expect and neither cheap. 

https://www.uk.hammerhead.io/products/hammerhead-karoo-2