Which laptop should I buy for heavy Internet usage (multiple eBay tabs)? Price range: upto £300 (pre-owned)

I'm looking at a price range of upto £300 (pre-owned) and have narrowed my search down to: Lenovo ThinkPad T420 (INTEL CORE i7 2nd GEN, 2.8GHz, 8GB MEMORY, 256GB SOLID STATE HARD DRIVE, NVIDIA OPTIMUS SWITCHABLE GRAPHICS 1600 X 900, WINDOWS 7 PRO 64 BIT, NEW 9 CELL BATTERY) or Dell Latitude e6230 (INTEL CORE i7 3520M, 2.9GHZ, 8GB MEMORY, 128GB SSD HD, WINDOWS 10 PRO) or Dell Latitude 3470 (INTEL CORE i5 6200U, 2.3GHZ, 8GB MEMORY, 128GB SSD, WINDOWS 10). Please mention any others if they are better than these selections. I will only use it for internet (eBay, email) and Excel. Factors that are not important at all are: battery life, graphics, look, condition, webcam, fingerprint technology, etc (I don't need any bells and whistles over the important aspects to me - I do have a laptop for personal use). I don't mind what version of Windows but I mentioned in case it affects performance). Thank you very much. I did spend a lot of hours narrowing it down and reading about Intel Core's etc as I had zero knowledge of computers. Please don't worry about factoring in price of the three mentioned laptops.