Welcome to the forum!
The solutions available to you in terms of electronic keypad locks have their own vulnerabilities, if you are looking for better security, you are better off going with a bump proof mechanical lock, in my opinion.
The Yale you linked to is an exception, but most electronic keypad locks have a mechanical key override, for when the battery runs out, or the electronics malfunction. These mechanical overrides are almost always locks that are vulnerable to bumping.
Electronic locks often also have a high failure rate, you will get better reliability from a bump proof mechanical lock.
The entry codes for most keypad locks are re programmable, so you aren't stuck with a factory set code, however the problem you highlight of other people learning the code still exists.
A possible disadvantage of these locks being reprogrammable is a disgruntled tenant changing the code on you when they leave.
Most bump proof locks also have good key control, this means that it is difficult to obtain duplicate keys, you can't just take them to a hardware store and ask for copies, because they can't make them. To have copies made, you must prove your credentials to a locksmith & usually present a security card that came with the locks.
If you feel that a bump proof mechanical lock may be a better solution, three you can look into are the Bilock, the Mul-t-lock MT5+ & the Abloy Protec. The Bilock is likely to be the most affordable of these. You will not find them in hardware stores, you will have to go to a locksmith. These locks are also much more difficult to pick than standard pin tumbler mechanisms.
Another advantage of Bilock is that they have a system called Bilock QC, that allows you to change the lock cylinder in a matter of seconds, so by having a few extra lock cylinders ready, you can rekey the locks at a given property yourself when there is a new tenant. A special key is turned in the lock & the cylinder comes out, then another cylinder is inserted in it's place and the lock is rekeyed. It is very fast & no tools are required.
A much cheaper bump proof lock is the Kwikset Smartkey. These locks are also quick rekeyable by the user, but they can be forced open fairly easily, so depending on the degree of security you require, they may be inadequate.
If I was in your position, I would choose a bump proof mechanical lock over an electronic keypad lock.
I hope this helps,