Faint line on one step but nothing on first response????

So im very early testing (only 10 dpo) but i have got the faintest 2nd line on 2 one step pregnancy tests now but then i did a first response hoping it would be darker cos they have a sensitivity of 6 whereas one step is 10 and there’s absolutely nothing on the first response?? Anyone else had this?

Also is one of these brands more reliable than the other?

One step ones are mega cheap so maybe not as good quality?? Any help/advice appreciated! Xx