I've been trying out a few different things for EVA recently and really haven't had any complaints on how they turned out, what's "best" can be based on a few different criteria. Price, durability, depth are all different things that you can be looking for so it's hard to say what's overall the best.
ODST
Heat seal + Platidip + Krylon ColorMaster Primer + Krylon ColorMaster main colour + brush on acrylics.
Salvatore
Heat seal + liquid latex + brush on acrylics
NCR Ranger
Heat seal + Rust-Oleum FlexiDip + Krlon ColorMaster Primer + Vallejo Model Air + brush on acrylics
These three are EVA parts from costumes of mine over the last 8 months. Salvatore was the quickest and dirtiest, it looked okay and passed the 10ft rule but man was it bad. It was cheap and easy but it looked the part of a cell shaded graphics game. Liquid latex smells like farts and is very prone to running, pooling and bubbling on smooth surfaces when brushed on but the non-toxic/non-flammable properties are a bonus. The only downside to it is the fact that if one small piece starts to peel up, the whole section is likely to unless resealed. I like it for things that are organic and goopy such as my
Flood armour add-on since it leaves a smooth, glossy surface to work with.
The ODST was the middle of the pack, relatively simple painting procedure but PlastiDip (at least in Canada) made it the most expensive of the three options while being the least labour intensive since it was basically spray, wait, spray, wait, spray, wait and then go to town with chip brushes. Plastidip has never peeled up, it just has brushed away with friction at points where foam meets foam such as knees or shoulders that scuff against other pieces.
The one I'm most happy with is my most recent with the NCR Ranger where I was trying out a new product and hoping for the best with FlexiDip. FlexiDip is $7 a can as compared to ~$20 for PlastiDip here so I thought it was worth a shot, it goes on thinner but overall I'm happy with it even after three coats when I was expecting to have to do six to make up for the lighter consistency. I also picked up an airbrush a few months back which has been slowly phasing me out of aerosol spray cans so Vallejo Model Air has been my go to so far due to their wide range of colours and at $3.50 a bottle if it's something I don't like, oh well, it was less than $5. For the blackened steel it was three different colours layered up and then chip brush for extra scuffing and mud which aren't on this photo but will be on the ones I post for my
build log in my thread later on this week after I catch up with real life stuff a bit. It hasn't shown any wear and tear after wearing it for an eight hour period of the weekend so I'm happy with it's strength but more testing is needed.
I realize I went on a tangent but painting is probably my favourite part of any build and I just wanted to show that there's no one right answer for what is best since I've tried probably a hundred different paints on projects across a dozen manufacturers and it's a lot of trial and error while going with your gut towards what you think will work best for the finish you want while still working on the material at hand.