Glad to help. Ilvl no longer directly correlates with stats in BGs, so yay! No white rings or necks or anything. Stats are actually stats. Many pieces of gear will follow the general pattern of having some primary stat, some stam, and usually some of two different secondaries (though sometimes only 1). Most greens, most dungeon gear, heirlooms, rewards from BG crates and dungeon satchels. So where applicable, you'll obviously want the highest ilvl you can get, which is usually 29 greens/blues....which are ilvl 33 or 34 (can't remember off the top of my head). And then obviously you'll want ones with the desired secondaries (which depend on class/spec/preference - but usually can't go wrong with verse being the primary).
BG crates can drop greens (not bad, but unremarkable) and blues (usually BiS, slightly higher ilvl than normal lvl 29 gear). So those are often BiS. Especially mainhand weapons for things like rogue, where weapon damage comes into play.
Some quest gear and BoEs don't follow that pattern - so true BiS often involves a few of those pieces. This is where a guide would come in handy. I know a lot of the 19 ones, but not the 29s unfortunately. Keep an eye on the AH for 26-29 BoEs with non-standard stats and see if they might be good. Something with higher than normal primary/stam and no secondaries might be useful. Something with no stam but int and haste might be a glass cannon caster BiS. Theres usually some primary only gear for glass cannon rogues and stuff. But remember thats all BiS and filling out niche sets - for the most part you should be good with heirlooms/dungeon gear/BG crates.
AFAIK, boomkin is godlike, arms/fury are solid. At 19 only outlaw rogue is viable. I know either assassin or sub gets a lot of important skills in 20-29, but I'm not sure which. The good news is that you can gear them all up somewhat, then actually pick the one you like.
I'd also take a look at the armories found in the stickied thread in the 20-29 section. It should give you an idea of what some people are running and some of the options. It might also help you find servers. My guess is bleeding hollow is the most active. But for the same reason any BoE gear is always expensive. Really expensive.
And then you can read the assumptions/sources sections of the 19s guide in my sig. The actual gear won't be too helpful for 29s - but a lot of the gotchas are the same (the way minor speed vs boar's speed works, glove reinforcements, neck/rings with primary stats, etc).