We went to keypad locks many years ago. Best thing we ever did regarding house entry and security. If you have a guest, you can set up a temporary code specifically for them, and then delete it when they're gone.
It is very convenient not to have to reach into your pocket to get keys out to enter your home.
The battery in ours (a Schlage brand model) is a 9 volt, and lasts for many years - I'm thinking it must have been a good 8 years before we had to replace the battery).
[edit] Wait, now I can't actually remember the battery type for sure. It may have been a CR123. But I think it was a 9 volt. [/edit]
If you get one, I would recommend one where you key in a code to enable the deadbolt, which you must then turn by hand. These are much stronger and much more reliable than the ones where you key in a code and then the deadbolt retracts under power from a small motor. These auto retracting ones often use cheap plastic gears and all kinds of other cheap innards. They are more toys than locks.
I would not get one that allows WiFi, bluetooth or other "smart home" activation. Too much of a security risk there for my liking. I want a good strong deadbolt that simply does not require a key to open. To my knowledge, they all allow backup key access. You are not buying one to get rid of a key, you are buying one for the convenience of not needing a key 99.99% of the time (unless the battery fails - which you get plenty of advance warning for - you'd have to ignore it for weeks/months to ever have a problem).
Ours is similar to this one (cosmetic differences, but functionally equivalent):
You can get just the deadbolt part separately. We got the additional handle with it to also replace the original doorknob. When your hands are full you don't want to have to turn a knob, and you can just lean down on the thumb paddle with your elbow and then push inwards with your body to open the door. You can also key in the code using your pinky finger or any other handy appendage and turn the deadbolt effortlessly with that same appendage. You don't have to grab the deadbolt - just kind of nudge it to turn it. Again, very handy when your hands are full.
This is actually what ours looks like (but minus the extra door handle shown above in the cosmetically different model):
( remove extra spaces around "amazon" in the link below - I don't seem to be able to post an Amazon link normally )
https://www. amazon .com/Schlage-BE365VCAM619-BE365V-Camelot-Deadbolt/dp/B000NJJ1MQ/ref=sxin_14_ac_d_rm?ac_md=0-0-c2NobGFnZSBrZXlwYWQgZGVhZGJvbHQ%3D-ac_d_rm_rm_rm&cv_ct_cx=schlage+keypad+deadbolt&dchild=1&keywords=schlage+keypad+deadbolt&pd_rd_i=B000NJJ1MQ&pd_rd_r=e4c2d165-e9d4-4b24-91ee-b72a75f42182&pd_rd_w=pFRvR&pd_rd_wg=JRbIa&pf_rd_p=c41d1f6c-956c-4fe2-8019-1663b7e1dd23&pf_rd_r=D8T2BVGV856V4FE0WASM&psc=1&qid=1631047369&sr=1-1-12d4272d-8adb-4121-8624-135149aa9081