ive driven x models, saharas and rubi's. automatics and manual. 2 doors and 4 doors. for the everyday driver id say an X model is fine. the sahara offers more interior options and color matched flares. bang for the buck the x model can get upgrades down the road, but if your sister just wants an affordable 4wd with plenty of capability out of the box then go with the x. i do find the auto versions easier to drive on the x and saharas due to the gear ratios and the engine power band. the rubis are nice with the manual trans because the diff gears are lower. thats just my opinion. if she doesnt need the space the 2 door will perform better due to less weight compared to the 4 door. but the 4 doors arent all that bad in stock form.
pm if you have any other questions.