The 7.3 would be my choice. It has an alloy fork, but that's life in that price range. Five year old parts will hold up just fine, as long as they're not wiped out now. There hasn't been any major advances in lower lever stuff in a long time. It takes time for top line technology trickles down. And usually doesn't reach the lower levels intact.

I've never heard of the Aguilla and am not going to search. You didn't find anything, so that's that. At that price and description I certainly would take a look.

One bike is listed as "20 inch/51cm" and the other as "small". It's not really a "which one should I buy" but a "which one fits you". That would be the one to buy.

A small frame doesn't reach 20 inches--both bikes are not suitable for you. You need to start your search with bikes that are your size.

I ride a small/17" bike, in that style.