In Path of Exile, Bringer of Rain also called BoR, which is very powerful especially a legacy one. You can get a ton of life on it, negating this argument for the most part. You also get decent block chance from it and the armor and evasion you get from the helm are pretty good as well. Having enough poe items will be an advantage for you.
If you don’t have access to a legacy one, you still get block and life, but less of it. However, one thing you can’t get from a 6L rare armor is 20-30 flat physical damage, which is huge. Additionally, the BoR gives you “free” Blind, which is pretty useful as a melee character.
With a 6L body armor, you miss out on a support gem, such as Blind, but you also potentially gain more defense, both in main stats (ARM/EVA) and in resistances. The high resistances you can get on the armor (and the helm I may add) would free up some mods on your jewelry and gloves to max out on DPS, making it a little easier to balance your character.
Sometimes it can be hard to cap resists with the BoR on and still have max movement speed, damage on everything, etc. It’s a little more work to min/max with the BoR. Also, since you can use a helm and have an additional 4L setup, you could do some interesting things, like add another Vaal skill, or use Ancestral Protector/Warchief or Decoy Totem. Really up to you and how much crap you want to manage.
If you want my opinion, and you probably know it already, I would take the BoR all day, every day. I keep my builds simple and cheap. And I always buy poe currency on U4GM.
In an ideal world with no costs, you could spring for a 6L Belly of the Beast and either a really good rare helm or a unique one. Abyssus would be maximum DPS, Rat’s Nest is generally good for a crit character and Starkonja’s Hood is probably in the right spot with some crit and a decent life roll on it. This all would let you probably out-DPS a BoR with 5 support gems at 20/20 and some extra crit on the helm, plus you’d have a lot more life. You would just be spending about 15 times the cost of the original build.