Topshop are my everyday jeans (I am 5ft, size 12 in the petite, 30 inch leg seems too big for me in 12, in the waist and leg), the Martha jeans are good, there are none online just now, but they are straight leg, so I think they flatter everyone.
Also worth a look in River Island, but again their short is too long for me, so I have to wear with heels, you have to search to find the right pair... I am considering paying more because I have struggled to find good jeans lately.
I used to really like New Look, but it has been a while since I bought any from there, they did at least fit perfectly in length and were very cheap.