I don't play every class, but I do experiment with a lot of builds on the ones that I do play. Build crafting is one of my favorite things to do in games that allow it, and there are so many possibilities in GW2.
Because some of the following builds are gimmicky or have a lot of counters I'm going to score them from A - C, A being highest C being lowest, for their viability. A would be something that can compete with meta builds, C would be something that is situationally strong.
By no means do I claim any of these builds to be perfectly optimal and in no way am I certain that they couldn't be improved. I have done a lot of tinkering with stats, traits, etc. to land on the builds I wanted and these are some of the ones I've used the longest/am the most proud of.
[Obviously all of these are roaming and/or small scale builds.]
Demonic Shroud - Scourge
Elixir Engineer is quite strong once in combat, but very vulnerable to openers and Condition bursts. A lot of its durability is reliant on high Protection uptime and multiple sources of regen, while its cleanse is dependent on blasts and single or small cleanses. Its damage isn't the greatest if you can't stay on the target or lock it down, but it can actually do quite high damage if you time your skills right, and especially if you're Might stacked. It has low mobility but extremely high durability which makes up for that slowness a bit.
Beast Master Ranger is surprisingly strong as well, but only particularly so in smaller fights and if you're good at managing your pet. Because the Ranger itself has extremely high armor and mobility you can focus entirely on buffing your pet, Vulnerability stacking and locking down your targets, and managing your pets for bursts. Felines with this build can easily do 6 - 8k auto attacks and 10k+ F2's. It's stronger than it looks.
Torment Scourge is "bad" because it has kitten for Corrupts/Strips and terrible Life Force generation, but oppressively high damage. It won't survive a long fight because it has no way to sustain itself, but it has tremendous Condition damage. This build can absolutely shred people with the amount of Torment and Fear it can apply, so the key is to always stay aggressive. As long as you can wombo-combo people it can pretty much melt anything.
Juggernaut Scrapper is a little awkward but has surprisingly good sustain through Barriers and Med Kit combos. It can pump out a lot of damage quite fast, has decent Condition cleanse, and is near perma-immune to CC. It even has moderate mobility to boot.
Gadgeteer Holosmith is probably the worst of these builds, but still quite fun. Absurdly high mobility and moderate damage, but very weak to CC and pretty much 0 burst. This is mostly a trolling build because it's so stupid fast you can outrun pretty much anything with it while also having enough damage to kill people if you need to.
The A tier builds should be pretty self explanatory. None are meta (to my knowledge) but are either inspired by meta or strong enough to compete. Some of them I have been using since pre-February patch and they still work well.
Feel free to adjust them to your preference. Some utility/rune/sigil/trait choices are entirely for my own comfort and aren't build defining. Most stats are however necessary to synergize with how I've crafted the build.
PLEASE DO NOT COME IN HERE INSULTING THE BUILDS
I'm 110% aware of their flaws and have spent plenty of time thinking on and adjusting them. If you think any/all of these builds suck, that's cool, but I don't need to hear it. I'm just sharing some builds I enjoy that I've had a lot of success with, and some that I've been using for a very long time. I hope they help someone who's in need of something new to try.
Necromancer / Engineer | Maguuma | Diamond Legend
[YWY] Weeping Valley //
My Youtube: Shroud