See, I do not understand your logic, if you just get win 10 you only get that, you get java and you get both, I find it that getting just win 10 is a bit redundant when there is a much better deal.
See, Geneo here is known from running around Java Edition forums bashing the Java edition every single chance he gets. Apparantelly using Java edition over Win 10 (which I call glorified Pocket Edition, as it's just what it is!) is "sticking with sinking ship".
See, I too struggle to understand his logic, as of course it's no brainer to get Java Edition, when he will get the Win 10 edition for free with it! So, you basically pay from 2 games, when in reality you pay from 1, you just get the second one free!
Windows 10 version is a complete copy of Pocket Edition. Java is the original and most updated one (with most new features out on it first, then those features get added to Windows10 version, pocket etc. etc.). Even if you buy Java version, you still get Windows 10 for free. Though you'll never use Windows 10 version after playing the original java version.
The Meaning of Life, the Universe, and Everything.
Get both. Play both. Experiment with options and settings, find out what works for you and what feels right. Bedrock seems to make more assumptions about what you want from it but doesn't stop you from doing things differently if you want.
The Java version has a demo that you can download and play for free. It's a little limited - it is a demo - but it will give you an idea of what you're getting for your money.
Disclaimer: I've been playing Java for three years but am a total noob in Bedrock.