First off, a disclaimer: I do not collect the physical card game. It's too time and money consuming to do so. I do, however, play the various video games based off it obsessively and keep close track of all the various trends and upcoming packs as best I can, so I'd like to think I'm approximately as experienced as a regular player.
Favorite deck or archetype? Don't have one. I love 'em all. Currently I'm on a bit of a Six Samurai bent, but that's a passing phase and I'm just as likely to go for Destiny Heroes, Dark Paladin, Crystal Beasts, Elemental Heroes, Armed Dragon, Horus, Volcanics, Six Samurai, VWXYZ, Gladiator Beasts, Gravekeepers, or even Ojamas if I feel like it. One of the benefits of sticking to the handhelds--I get to try them all out at a whim.
I tend to let other people handle the more technical aspects of doing this wiki; I like filling in as many card tip pages as I can when I think it's appropriate to do so, since some of them are lacking. Lately a thing I've been doing is filling in general strategy tips, play style descriptions and weaknesses portions on deck and Archetype pages, to give a better general impression of what those card groups are like when properly played.
I'm working on perfecting an anti-Gladiator Beast deck right now by making it flexible enough to be competitive against things other than just Gladiator Beasts (the anti-special summoning aspect is the most important, it shuts down a lot more than just Gladiator Beasts, great against Fusion and Synchro decks, too).
Everyone has their own idea of a great Archetype. Mine would be something called "Scrapyard Monsters," which would focus on the use of two spell cards, "Worthless Junk" and "Worthless Scrap." The "worthless" cards cannot be normally activated--instead, like "Ojamagic," they do their thing when sent from the hand or field to the Graveyard. They each search out a copy of the other type of "Worthless" spell card when they do this. The "Scrapyard" monsters use their own effects to do different things with the "Worthless" cards. One turns them into equip spell cards for itself (and gains a different effect depending on if it's Scrap or Junk), a few send them from the hand or field to the grave for different effects, and one recycles all of them in the Graveyard to the Deck to power itself up for every "Worthless" card returned to the Deck.
I also have another dream archetype, "Radioactive" monsters. They're all LIGHT - Thunder type monsters, and most of them do burn damage to the controller during their End Phase. They gain devastating effects when the user's Life Points are lower than the opponent's. "Radioactive Zombie" revives itself to the field if you take a certain amount of damage during the End Phase from your other monsters, "Radioactive Brute" (a Hulk reference) doubles in power when Life Points are lower than the opponent's, and "Radioactive Contaminator" lowers the ATK and DEF of opponent's monsters by 100 for each "Radioactive" monster in the graveyard. The trump card of the set, "Super Radioactive Dinosaur - Galogoth"' (who is a Godzilla reference), does 1000 burn damage to BOTH players during each player's End Phase, and can optionally be Special Summoned from the hand if the user's Life Points are 3000 less than the opponent's or less than 3000 total. To keep from destroying yourself entirely, the Field Spell card, "Radioactive Wasteland" gains a new effect depending on how low your Life Points are. At 1000 Life Points left or less, you stop taking any damage at all, from battle or effects. (But if it is destroyed, you obviously will be in grave danger of losing, so it's a precarious position.)