Samsung Galaxy S — Android OS update

Hi, I'm looking for a new Android phone from Straight Talk, and I was wondering your thoughts on this. I've never really had a "Smartphone before, and am excited to be able to use various apps and games. The Samsung Galaxy Grand Prime has an updated version of the Android OS (it is 5.0), and a better front face camera (which is 5 megapixels). That being said, the Huawei Raven has a better display which is 1080 x 1920 (compared to the Galaxy Grand Prime's 960 x 540 display) and seems like a sounder phone overall. I'm in a bind here, as really the deciding factor is my concern over the Raven's OS (which is Android 4.4 KitKat) becoming outdated shortly after I buy the phone. To give a few more details my price range is about $200, and I'm staying with Straight Talk. I'd really appreciate any advice on this matter, thanks!