I take cypionate nowadays (because of the shortage) but I've previously taken valerate, too.
Estradiol Valerate (EV) and Estradiol Cypionate (EC) are two different esters of bioidentical 17b-estradiol; they are "pro-drugs," meaning that the body processes the molecule first, cleaving off the 17b-estradiol molecule from it attendant salt where it then can do its magic. The cypionate ester differs from the valerate ester in that it generally takes the body longer to perform that "cleaving" -- possibly because cypionate is lipophilic.
Regardless, what it means is that whereas peak estradiol levels generally occur about two days after injecting EV, serum levels peak in more like 4 days for EC. The EV peak will be higher than the EC peak, but EV will "drop" quicker as well, getting processed out of the body in about 7-8 days, whereas EC will take 10-11 days to leave the system.
I've enjoyed both forms, but if anything I like the "smoother ride" of EC; with EV I'd have to inject 4 times a month, whereas with EC it's only 3 times a month.