RMIs you'd keep to the very end

One thing I like to do between sessions is daydream about what equipment loadouts my Artillerist could carry. By level 6 things get really interesting, with the ability to craft some uncommon magic items plus access to the epic Magic Item Tinker.

It seems to me that the best RMI options are mostly items with charges, which you can create with a full charge every day and then drain for an extra spell slot or transform into something else. Or, recharge them instantly and keep using them, something no other class can do!

The spell-refueling ring, with its ability to basically give an artificer two extra spell slots (or a spell slot and a different item, or two extra cannons, etc), sounds useful all the way from 6 to 20.

Repulsion Shield also seems pretty nice, with its four free charges of push each day. If your DM is nice, they'll let you create it as a +2 shield at level 14 based on AU's new evolving magic items rules.

Wand of Web's seven free castings of Web (which you can then drain for a spell slot), though the DC is a little low in late-game.

At level 10 you can make your own Ring of Protection and Luckstone, if your DM hasn't given you one yet.

Beyond that I haven't really researched it much, but AU's Blood Amulet combined with the artificer's ability to recharge the item is really powerful.

So what RMIs are must-haves for your artificer through most of their career?

I find myself surprised that so many people like wand of web as a replicated item given the preciousness of each slot. Web is a great spell, but the wand can only be attuned by a spellcaster, it still requires concentration, the DC is lower than my native DC, and I can't say that I've ever had an adventuring day where I've wanted to cast it more than say twice. What am I missing?

By contrast, my homunculus runs about with the Wand of Magic Missile and that gets quite a lot of use.

Some of this depends on the prevalence of magic items available at your table. Hopefully you can replace many of the lower level items with permanent items - your Bag of Holding, your +1 armor, Repeating Shot, etc. Repulsion Shield is great, Cloak of Elvenkind can be useful for a long time. You also may be finding attunement slots to be a limiter, again depending on what's available to you. 

Ideally for the things you always use, you can set those up as permanent items, so that your replicate slots can be used for situational purposes - one day it's a Ring of Mind Shielding, the next day a Decanter of Endless Water.

Fortunately my DM is pretty good about giving us magic items. And he's set up a path towards making some RMIs (like bag of holding and my beloved repeating heavy crossbow) into permanent items. So for example at level 3 our bag of holding is currently occupying one of my slots but I've already collected nearly all the materials I need to make it permanent by the time we hit level 4.

Hmm, you're right about wand of web. Perhaps I'll demote that one from my must-have list and let one of the other spellcasters in the team handle that one!

I think Sentinel Shield is probably one of the most underrated items on the RMI list, adv. on perception and initiative on a +1 shield is great....