which category of meds helps diastolic/systolic numbers

[avesls]

I am currently taking three different bp meds - diovan (angiotensin II blocker), metaprolol (beta blocker) and HCTZ (diaretic)  I am almost at a point where I can decrease one of them.  My bp has consistently been at 100/75 for a few weeks and historically it will go to 90/70 soon, so I need to decide which to decrease.  At this point each is at it's lowest dose, so I should eliminate one.  My doctor says I know my body best and having decreased meds annually for quite a few years I think she is probably right.  I know the side effects of each and the benefits to decreasing each, but I wonder if one or another is better for lowering the top or bottom number.  I seem to get very tired when it goes too low and yawn constantly.  I would prefer to decrease the beta blocker if all things are equal, but if the beta blocker is more effective on the lower number, it might make more sense to decrease the diovan.  I am not considering cutting out the HCTZ because it is the first line defense and the least invasive to my body.  Anyone know if one of these meds impacts one of the numbers more than the other?  the literature doesn't say.