I agree on you taking a logical look at this and I admire that you’re trying to get help. I hope you can find some insight with my advice. Trusting your love of fighting games enough to go for any one of them is very admirable. But beware, leaning on thoughts like investment and what’s highly regarded is anchoring yourself with strangers in a strange land.
“Defensive”, “Offensive”, and “Niche”-your fighting affinity pretty much decides how you classify fighters.
I see Soul Calibur as a Niche game, where offense and defense can blend pretty well due to a unique system with varied styles and pacing that puts you in an atypical zone to get back and forth.
Based on that, I’d recommend Tekken. You are already used to a similar pace and it can actually be more stable than Soul Calibur, which would give you an advantage in the learning curve. However, the community may be moving to Tekken 7 soon, so be on your guard if you’re trying Tag 2(the latest iteration) for full price or something.
I would recommend Super Smash Bros, most definitely a niche to me, but I don’t know if 4 is as defensive as it’s predecessor was. The online community for any Nintendo game is going to be ridiculous though, this can really help if you’re the type who can learn from advice and want a lot of online support to play against gamers no matter what time of day.
Last suggestion for me is Ultra Street Fighter. Leaning on niche in my humble opinion, but mostly a defensive fighter. You will rarely see no one online since this game is technically new (about 6 years old but an updated version), plenty are playing and talking about it, so you’ve got a community to lean on for advice. But beware, it really is highly defensive, I only named it because Mortal Kombat seemed defensive to me last time I played it. But the last time I played it was on SNES!!
Thank god you aren’t an Offensive, KOF has almost nonexistent community support but it’s a great fighter to learn the basics from, though Blazblue does that extremely well too, especially with their crafty A.I.(and I mean REALLY crafty).