which thinkpad i'm looking for

[pepsy]

Hello
first of all, I didn't found a presentation topic so I'll do it here
I'm Alessio, 24 yo from italy. Atm I'm studying computer science and i'm looking for a laptop.
After years of dell i decided to switch to a thinkpad but I'm getting a little confused.
The more i look the more i get confused.
I started from the t430, then i found the s models, then the t520 with mechanical keyboard (I have a thing for mechanical kb)etc.
I need a long lasting battery (i know that tp have a supplementary battery that is optional, so i need that it will be available), the possibility of put 2 drive in (i don't care if it is through m2 or in the optical bay), a screen that doesn't tire my eyes (i expect lot of hours of coding with it) and a good keyboard it's a good plus(it seems that all tp keyboard are pretty good)
I don't really need a lot of power though i expect to use it some years and I will do some graphic works(nothing heavy).
I don't know if the t430 or t520 are too old for what i need, if they have old bad screen or other thing that i should know.
I have 800€ budget so i can afford also some used t440, but i prefer don't spend all that money if i don't really don't need it.
I hope I have not missed a more appropriate section for post this type of request.
Thanks