All are upper arm types as follows:
1. a Rite Aid deluxe automatic model BP3AR1 which is the top rated model in Consumer Reports. I just bought this one a few days ago.
2. A ReliOn model BP 200 upper arm model from Walmart, which is also one of the top rated machines in the Consumer Report's guide.
3. A CVS Premium upper arm blood pressure monitor, model BP#MV1-3WCVS. This was Consumer Reports top rated model when I bought it nine months ago, but it has dropped in the ratings since then.
All three of those give relatively consistent readings, usually but not always within 10 mm hg systolic of each other. Diastolic is more uniform, but still 10 to 20 higher than I get manually. On occasion the systolic difference is bigger, sometimes almost identical.
An older model Eckerds semi-automatic electronic model E7623. You pump it up manually with a bulb, then it releases air automatically and gives the reading electronically. This unit just recently quit working due to an air leak, but until that happened, gave the same results I get with a manual aneroid cuff and pretty close to what my doctor gets.
An older (20-30 years old) blood pressure cuff with an aneroid gauge and a stethoscope. It always gives me a much lower reading on both systolic and diastolic than I get with my automatic electronic cuffs. I have tried swapping out the gauge for another one I have from an old cuff and get the same results. The stethoscope does not attach to the cuff.
I have about five stethoscopes, all are the inexpensive type that come with manual blood pressure cuffs or that came from a hospital when my mother in law was hospitalized a few weeks from a fractured femur and developed MRSA. A couple of my stethoscopes came from the "infections disease control" supplied to her in the hospital.
I learned to take blood pressure the old fashioned way 40 years ago as an ambulance attendant and EMT. Usually I tuck the stethoscope under the bottom edge of the cuff, but sometimes hold it or have my wife take it to make sure I'm getting an accurate reading with it tucked in under the cuff. It doesn't seem to make any difference which stethoscope I use.