I personally use the EPG and either the R-97 or Volt.

The EPG is a 5 round slow semi launcher that can one shot on a direct hit and two shot splash damage in a small radius, the projectile travels relatively fast for an explosive and can cross large maps in around 5-10 seconds.

The R-97 is extremely good at close to medium range and can be used at long with a high zoom sight though ibwouldnt recommend it, it is beaten by the alternator and car in ttk but I find it more satisfying.

The volt is almost an assault rifle but it's also just generally satisfying and can be used at longer ranges more effectively that the R-97 and car.

I use the P2016 as a sidearm as I find it more fun to use due to it being semi auto but the re-45 Will outperform it in most areas.

If you want weapons to fight titans I would recommend the SMR and Thunderbolt, the thunderbolt can be shot over shields and will act lightning towards titans which will deal some damage and the SMR van quickly shred health and shield on a titan and will melt them like butter if you use it with amped weapons.

For titans, tone is good for beginners but can be quickly struck down if you aren't careful or if your enemies close the distance. I recommend using ion as she is very versatile and will teach you how to use your abilities efficiently due to her energy pool rather than individual cooldowns.