Help me decide!!!

hello i'm currently managing arsenal and currently on the january transfer.
I want to strenghten my left back side so i do some scouting for some good candidate and found two, Aly Cissokho and Alex Sandro. Can you reccomend me which is better, or please suggest me if you have better reccomendation.

Sorry for my bad english.

If you have the funds, Aly Cissokho is definitely a better choice for left back. If you're willing to spend lots on a left-back, check out Domenico Criscito. For a cheaper option (besides Sandro), see Martin Olsson. Hope this helps.

Leighton Baines(Everton) and Tremoulinas(Bordeaux) would be good options for your left side of defence.

I like Andreas Beck or Marcel Schmelzer... although Martín Montoya is also excellent (not sure if he's on the left side or the right...

It sounds obvious but Philip Lahm is immense. Expensive though....

although he is more expensive than Sandro , i will pick aly cissokho , he is good fullback

but in my case alex sandro is more expensive than Cissokho
I also heard that alex sandro becomes good in the future.

Aly Cissokho turned out shit for me at his club and never plays now