Monk vs Water
Monk is better. Just looking at the wiki pages. The monk 4 piece does not scale with healing power so 690×4= 2760heal a minute. The 10% heal to allies will add 600 extra healing to allies with just arcane evasion and water traits, anytime you swap to water and dodge. Swap to water 6 times a minute 3600 extra healing to allies. Water runes 6 piece 690+750(1500healing power) after every heal. With ether renewal 4 heals a minute 6740 extra healing to nearby players.
Water runes give you 6740 extra heals and a condition removal. Monk runes give 2740 self heals and 3600 extra heals to allies from traits alone. Monk is better for healing allies and water is better for healing yourself.
“Quoth the raven nevermore”
Platinum Scout: 300% MF
It mainly depends on if you want to maximize your allied healing or not.
In most cases I would advise using the water runes, simply because you get a bit of extra boon duration and your self healing will be better overall. The 6 piece bonus is really handy, especially since it will heal allies as well as yourself. I also feel the condi clear on-hit tends to be more powerful than the heal on-hit, although this might not be the case if you already have very good condition clearing.
Monk runes only really shine when you’re specifically focused on healing allies. I use them on my 02066 magi/cleric ele that is deeply focused on healing, which also uses a sigil of benevolence. If I was playing a more balanced build, I would probably opt to use water runes (unless I was building for a specific group comp that necessitated monk runes).