I have used Echo, then Sigma, then VDO. All have been quite solid and well waterproof. All manufacturers have a basic model that covers all your needs, and most if not all are waterproof enough to take as much rain as the rider can tolerate. If the thing cannot stand rain, it should be mentioned in the box or documentation. Such a comp has very limited use.

My first, extremely basic Echo3 -computer did not have the clock feature (though obviously it had timing circuits), but with Sigma I grew accustomed to check the time from bike comp. I don't even own a wristwatch. I don't know if any of the current entry-level models come without clock.

--J