I know the wondfos have had bad batched but honestly I have not had bad tests from them, I have a couple of evaps out of around 150 tests but nothing else. I do like them because they are cheap so I can poas when I feel like it and I have seen ladies get very early bfp's on them, even some that got bfp's with a beta level of 4. One thing about them is they are slow to develop, even with my loss last cycle my hcg was 19 and it still took forever for the the wondfo to develop a good line, and the lines I got at 10 dpo were likely after the time limit, but were real.
This is where I get mine, they ship very fast and not a bad price either.
HCG Pregnancy Test Strips with Sensitivity of 25mlU/mL - Pack of 20 Strips | eBay
Other than that I use answer tests. Hope this helps. Oh I also hear that the wondfo cassette tests are even better that the dip strips, not sure how true that is but I think I will get some for next cycle to try out.