What Weapon Should I Buy In The Titanfall 2 Open Beta?

I'm 50 credits away from having enough for one of any of these items. Ultimately its a test to see if I can obtain any of the weapons over the beta's level cap, but I want one that I can enjoy. I tried the alternator that was dropped from a grunt and I have to say its pretty shitty unless your in cqb, but if you're going to be in cqb you might as well be using a shotgun Edit: I grabbed both the alternator and the mastiff from dead specters. Not that impressed with the alternator, and I didn't get enough pilot kills with the mastiff to know if I like it. Since the level cap is going to be raised next weekend I figured I might as well get the weapon that is the highest level, so I'll be buying the epg-1. 494 credits, I'll update here with my experiences of it Edit 2: First impressions of the epg-1: Its a ball of electricity similar to the anti titan weapon, but smaller. The speed is slightly faster and does not zap enemies its near as it flies. Upon hitting an object it lets out a very large explosion. Enemies near the explosion will take damage, and if the projectile hits an enemy pilot they will die instantly. Updated op with a link to some gameplay. Its great for taking care of campers/snipers, but is more difficult to hit a moving target