Like some others here, I normally play CoF but decided to give MG a go this time around with the bonus favour gain. So far it’s been a good experience, but there are a few things that I find frustrating.
Faction ranks
The issue with MG ranks has been brought up before, but I wanted to weigh in anyway. While I like most of the CoF bonuses and strive to reach some of them, the MG ranks leave me feeling frustrated. I think this is largely because the CoF bonuses feel like actual bonuses, whereas the MG ranks feel like the game is stopping me from playing the way I want.
I can see the ability to purchase LP uniques and legendaries as a goal to strive for and I can still flesh out my build for empowered monos using normal uniques and exalteds, so restricting when I can buy LP and legendary items seems reasonable. But the restriction on uniques and exalteds doesn’t feel the same since they’re an important part of progression towards the end game. On top of that, splitting ranks out between weapons, armour and accessories just looks like padding to fill the 12 ranks.
I know it would be a substantial amount of work, but I would like to see most of the restrictions removed or at least merged into the first few ranks. Then you could add more interesting ranks, such as merchant quests that could reward favour or gold or rare items if you fulfill them. Anything that adds some flavour and feels like a bonus rather than a restriction would work.
No list of recently sold items
I’m not talking about the items the player has sold here, but all sales that match the search criteria. Perhaps I’ve just failed to find the feature in the Bazaar UI, but back when I played Lost Ark I relied on the prices that items actually sold for to get pricing information, not the prices of the listed items. I don’t really see how prices are supposed to stabilise when no one knows what items are actually selling and what they’re selling for.
If you actually can view this information, could someone please let me know how? 
No way to “bookmark” items or save searches
When I’m browsing for items, sometimes I’m interested in a particular item but want to check if there’s anything better available. So it would be nice if I could easily get back to it a later stage. Whether it’s called bookmarking or favouriting or whatever doesn’t matter.
In addition, it would be nice to save searches so that I don’t have to fill all the search fields again each time I want to look for the same thing.
For what it’s worth, I think both these features are in Lost Ark’s auction house if I remember correctly, and I used them extensively.
Honestly, I can see the Bazaar being a massive time sink for the team, but I hope you have the resources to continue to improve it. I think it works well for times where I want to experiment a lot with builds without the drudgery of finding appropriate gear. And I think reworking the faction ranks to incorporate more interesting mechanics would help a lot with player engagement.