Which version of star diagnosis to buy

1. To buy best quality Star C3 2015.5 $459: 
Recommend you Star C3 Pro 2015.5 with 5 pieces of cable, it is the best quality and most stable, for  $459 not with shipping cost
Even the middle box in RS232 to RS485 cable is made by metal. 

If you select one that does not include the hard drive, they are cheap.
2. To buy cheaper Star C3 for $359
Recommend Star C3 Pro 2015.3 with read head and with 7 pieces of cables. It has the same function as best quality Star C3.
It is $359, $100 less than best quality C3.  http://www.MBStarTool.com/wholesale/-star-c3-pro-with-seven-cable-mb-truck-cars.html
3. SD C4 for $539 - most technicians highly recommend  
1) Actually the SD c4 is highly recommended, The SD c4 is more up to date, SD c4 clone is faster.
2) Compared with Star C3, SD C4 can communicate by WIFI/wireless, support UDS protocol, work with a part of truck.
SD C4- Truck Support List:
Actros963/4,  Actros2,3,  AtegoIII,  AtegoII,  AxorII,  Eonic,  Zetros,  Actros,  Atego Light,  Atego Heavey,  HPN M96,  Atron,  HPN M2000,  SKL,  FSK,  Further model series.
3) to pay extra $39.99 and get Vediamo V5.00.5, with this software, you no longer need to apply online programming or online to change the SA. You can now use Vediamo any offline for car program, setting code, change the SA Code function.
4. To buy Star with internal hard drive or external hard drive
Both Star C3 and SD C4 are available with external and internal hard drive, to buy external hard drive or internal hard drive; it is specific to individual users. According to most users’ feedback, I conclude their advantages and disadvantages as follows. 
External hard drive advantages and disadvantages:
1) External hard drive is a much more versatile solution. If laptop broke, you could just plug it into another machine.
2) It’s a lot slower than running it from disk, because of VMWare overhead. If you use it 2 or 3 times a year, a VM solution is perfectly fine.
3) Hangs off the machine and can be damaged as you move the laptop around. If you pick up the laptop, the USB drive unplugs, then it will fall to the ground and you’re cooked.
Internal Hard drive advantages and disadvantages:
1) To minimize setup difficulties I recommend purchasing a kit which includes an internal hard drive with all software pre-installed.
2) Much faster, if you use it quite a bit then go External hard drive.
3) Internal is so much nicer because now I just have the multiplexer and laptop to carry to the car. Nothing to unplug or fall off.
These months, many people would purchase SD C4 unit and pay extra Dell D630, they think it’s worth every penny… just takes some time to get to learn how it works.