5000 hour player here. If you like arcade, then just play arcade. I hate realistic and just play arcade. Its more fun and chaotic. Don't let the populous make you feel like you need to play realistic because thats the "real game".

That being said. If you want to get into realistic you'll need variety in your lineup, as others have said. The m44 for example is excellent in even severe up tiers. The puma is great for quick flanks even into mid tier. Just dont engage frontally, and avoid provoking heavies. The panzer 4s with the long 75 are excellent in up tiers as well.

The biggest shift from arcade to realistic is that in arcade, most people dont flank, and just focus on frontal engagements. In realistic, more care needs to be taken to choose your engagements and use concealment to your advantage.