Bettas can unpredictable with tank mates, just gotta try 'em and find out. Each one is unique. One of the reasons I love them so much because they have distinct personalities.
Any particular kind you were thinking of getting? I had a crowntail female that I absolutely adored. She was an anomaly, too. She was 4 inches long (absolutely massive compared to her 2ish inch "sisters"). Didn't know this until after I got her but since she was solid purple, she was super rare. Like a god damned, rare, living Pokemon. Had I put her up for sale she could have fetched a little under $1,000, but she was my baby and I didn't need money so I kept her til she died last year.