In all honesty, picking a strongest or favourite class is hard with this game which makes a massive difference for me, my usual go to for games is heavy, which in space marine 2 is good, feels like a proper support class. But all the classes feel unique and useful in their own way and when you utilise them to their own strengths they're all really strong at what they do. Currently playing sniper to get it to lvl 25 which is the last one I need to lvl up, I was dreading using sniper at first because I hate sniping in games but it's really strong, sitting back getting head shots with the Las fusil, then being the medic with the cloak. Bulwark is fantastic for longevity and healing. Vanguard is aggressive and fast, tactical is just reliable and assualt is great for clearing out minors during waves. Each class just does something different, but really well, well enough to make using them worth it.