Today, I'm going to compare these three units and highlight the good and bad of each one.
Vanguard Vets for Blood Angels are simply better than their C:SM counterparts. Not only are they cheaper, but they have Descent of Angels ontop of Heroic Intervention. Vanguard Veterans can reliably come in at the right place and the right time to assault anything in the game. They can take special pistols, carry power weapons and use meltabombs against those stationary artillery units. The best thing about these guys is their ability to come down and turn the tide of battle instantly. If you're stuck in combat with a squad that's wearing you down or if you're getting bombarded from afar from some artillery vehicle, Vanguard Veterans can save the day.
For these guys, I prefer a cheap and effective layout:
5x Vanguard Veterans (3x PW, 2x MB) = 205
Keep in mind that the squad leader already comes with a power weapon so you're only paying for 2 more. For these guys, a Power Fist is another strong investment because of the 2 base attacks, but I prefer Power Weapons and Meltabombs instead. The reason why is because they're supposed to act as a counter-charge element that can free up tarpits (near a FC/FNP bubble) or destroy non-moving vehicles. This is why my cheap squad has 3 guys with power weapons. The rest of your army should have fists already so I'm not really worried lack of S8 on these guys.