Well stealth is a great ideal but or most its never as stealthy as they intended.
Everything makes some noise.
All I can say is if you want stealth then you need a quiet fan, a bigger fan and filter run at lower speed will be quieter than one running at max speed.
Never buy a fan that doesn't provide decibel rating.
In some sense using a quality LED will reduce the total heat which will mean less air exchange needed which will mean less noise overall.
A quality fan and quality filter are important, quality fans wont rattle like cheap ones, quality filter will clean your air properly.
You can buy the quietest products on the market but your air circulation will still make some noise.
Customising an old wardrobe to fit a tent inside can offer some added protection, a grow tent will always look like a grow tent and if anyone sees it they will want to know what it is.
The best thing you can do for stealth is keep your mouth shut and tell nobody.