I have never found anything quite as complete as BIAB when it comes to putting together complete tracks that sound great. That's why I keep sending my money every December for the past 12+ years!

However, I do really love the EZ lineup from Toontrack. I have their EZ Bass, EZ Keys and EZ Drummer products and find them to be quite capable even compared to BIAB bass, keys and drums. I often create songs in BIAB and then sub out some or all of these parts with their EZ counterparts because they sound great and are editable MIDI. I think what Toontrack is missing is more melodic instruments like guitars, horns, etc.

If Toontrack were to add melodic instruments, build an aggregator GUI and curate their tracks into style sets they would have a very competitive product to BIAB. But, as a good friend of mine likes to say, "IF the dog hadn't stopped to do his business he'd have caught the rabbit!"